diff --git a/js/autocomplete.js b/js/autocomplete.js
index 832a82862..c799cc36a 100644
--- a/js/autocomplete.js
+++ b/js/autocomplete.js
@@ -15,127 +15,108 @@
  * @copyright  2008-2015 Horde LLC
  * @license    GPL-2 (http://www.horde.org/licenses/gpl)
  */
-var IMP_Autocompleter = Class.create({
-
-    // ac,
-    // acTimeout,
-    // box,
-    // cache,
-    // data,
-    // dimg,
-    // elt,
-    // elt_ac,
-    // input,
-    // itemid,
-    // knl,
-    // knl_status,
-    // lastinput,
-    // p,
-
-    initialize: function(elt, params)
-    {
-        var active;
-
-        this.cache = $H();
-        this.itemid = 0;
-        this.lastinput = '';
-        this.p = Object.extend({
-            autocompleterParams: {},
-            // Outer div/fake input box and CSS class
-            // box (created below)
-            boxClass: 'hordeACBox',
-            boxClassFocus: '',
-            entryDelay: 0.4,
-            // CSS class for real input field
-            growingInputClass: 'hordeACTrigger',
-            // input, (created below)
-            // <ul> CSS class
-            listClass: 'hordeACList',
-            listClassItem: 'hordeACListItem',
-            loadingText: 'Loading...',
-            loadingTextClass: '',
-            maxItemSize: 50,
-            minChars: 3,
-            noResultsText: 'No Results Found',
-            noResultsTextClass: '',
-            onAdd: Prototype.emptyFunction,
-            onBeforeServerRequest: Prototype.emptyFunction,
-            onEntryClick: Prototype.emptyFunction,
-            onServerSuggestion: Prototype.emptyFunction,
-            processValueCallback: Prototype.emptyFunction,
-            removeClass: 'hordeACItemRemove',
-            requireSelection: false,
-            shortDisplayCallback: Prototype.K
-        }, params || {});
-
-        // The original input element is transformed into a hidden input
-        // field that holds the raw return value.
-        this.elt = $(elt);
-        this.elt.writeAttribute('autocomplete', 'off');
-
-        // Create an autocomplete input element that holds the JSON encoded
-        // return value.
-        this.elt_ac = new Element('INPUT', {
-            name: this.elt.identify() + '_ac',
-            type: 'hidden'
-        });
-        this.elt.insert({ after: this.elt_ac });
+var IMP_Autocompleter = function(elt, params) {
+    var active;
+
+    this.cache = $H();
+    this.itemid = 0;
+    this.lastinput = '';
+    this.p = Object.assign({
+        autocompleterParams: {},
+        // Outer div/fake input box and CSS class
+        // box (created below)
+        boxClass: 'hordeACBox',
+        boxClassFocus: '',
+        entryDelay: 0.4,
+        // CSS class for real input field
+        growingInputClass: 'hordeACTrigger',
+        // input, (created below)
+        // <ul> CSS class
+        listClass: 'hordeACList',
+        listClassItem: 'hordeACListItem',
+        loadingText: 'Loading...',
+        loadingTextClass: '',
+        maxItemSize: 50,
+        minChars: 3,
+        noResultsText: 'No Results Found',
+        noResultsTextClass: '',
+        onAdd: function() {},
+        onBeforeServerRequest: function() {},
+        onEntryClick: function() {},
+        onServerSuggestion: function() {},
+        processValueCallback: function() {},
+        removeClass: 'hordeACItemRemove',
+        requireSelection: false,
+        shortDisplayCallback: function(x) { return x; }
+    }, params || {});
+
+    // The original input element is transformed into a hidden input
+    // field that holds the raw return value.
+    this.elt = document.getElementById(elt);
+    this.elt.setAttribute('autocomplete', 'off');
+
+    // Create an autocomplete input element that holds the JSON encoded
+    // return value.
+    this.elt_ac = document.createElement('INPUT');
+    this.elt_ac.name = this.elt.id + '_ac';
+    this.elt_ac.type = 'hidden';
+    this.elt.after(this.elt_ac);
+
+    this.box = document.createElement('DIV');
+    this.box.className = this.p.boxClass;
+
+    // The input element and the <li> wrapper
+    this.input = document.createElement('INPUT');
+    this.input.autocomplete = 'off';
+    this.input.className = this.p.growingInputClass;
+
+    // Build the outer box
+    var ul = document.createElement('UL');
+    ul.className = this.p.listClass;
+    var li = document.createElement('LI');
+    li.appendChild(this.input);
+    ul.appendChild(li);
+    this.box.appendChild(ul);
+
+    // Replace the single input element with the new structure and
+    // move the old element into the structure while making sure it's
+    // hidden.
+    active = this.checkActiveElt(this.elt);
+    this.elt.replaceWith(this.box);
+    this.elt.hidden = true;
+    this.box.appendChild(this.elt);
+    if (active) {
+        this.focus();
+    }
 
-        this.box = new Element('DIV', { className: this.p.boxClass });
+    // Look for clicks on the box to simulate clicking in an input box
+    this.box.addEventListener('click', this.clickHandler.bind(this));
 
-        // The input element and the <li> wrapper
-        this.input = new Element('INPUT', {
-            autocomplete: 'off',
-            className: this.p.growingInputClass
-        });
+    // Double-clicks cause an edit on existing entries.
+    this.box.addEventListener('dblclick', this.dblclickHandler.bind(this));
 
-        // Build the outer box
-        this.box.insert(
-            // The list - where the chosen items are placed as <li> nodes
-            new Element('UL', { className: this.p.listClass }).insert(
-                new Element('LI').insert(this.input)
-            )
-        );
-
-        // Replace the single input element with the new structure and
-        // move the old element into the structure while making sure it's
-        // hidden.
-        active = this.checkActiveElt(this.elt);
-        this.box.insert(this.elt.replace(this.box).hide());
-        if (active) {
-            this.focus();
-        }
+    this.input.addEventListener('blur', this.blur.bind(this));
+    this.input.addEventListener('keydown', this.keydownHandler.bind(this));
 
-        // Look for clicks on the box to simulate clicking in an input box
-        this.box.observe('click', this.clickHandler.bindAsEventListener(this));
+    this._watchInterval = setInterval(this.inputWatcher.bind(this), 250);
 
-        // Double-clicks cause an edit on existing entries.
-        this.box.observe('dblclick', this.dblclickHandler.bindAsEventListener(this));
+    document.addEventListener('AutoComplete:focus', this.triggerEvent.bind(this, this.focus.bind(this)));
+    document.addEventListener('AutoComplete:reset', this.triggerEvent.bind(this, this.reset.bind(this)));
+    document.addEventListener('AutoComplete:update', this.triggerEvent.bind(this, this.processInput.bind(this)));
 
-        this.input.observe('blur', this.blur.bind(this));
-        this.input.observe('keydown', this.keydownHandler.bindAsEventListener(this));
+    this.reset();
+};
 
-        new PeriodicalExecuter(this.inputWatcher.bind(this), 0.25);
+IMP_Autocompleter.prototype = {
 
-        document.observe('AutoComplete:focus', this.triggerEvent.bindAsEventListener(this, this.focus.bind(this)));
-        document.observe('AutoComplete:reset', this.triggerEvent.bindAsEventListener(this, this.reset.bind(this)));
-        document.observe('AutoComplete:update', this.triggerEvent.bindAsEventListener(this, this.processInput.bind(this)));
-
-        this.reset();
-    },
-
-    triggerEvent: function(e, func)
+    triggerEvent: function(func, e)
     {
-        var elt = e.element();
-
-        // IE 8 fix
-        if (elt == window && elt.document) {
-            elt = elt.document;
-        }
+        var elt = e.target;
 
         switch (elt) {
         case this.elt:
-            e.stop();
+            e.preventDefault();
+            e.stopPropagation();
             /* falls through */
 
         case document:
@@ -150,7 +131,6 @@ var IMP_Autocompleter = Class.create({
             return (document.activeElement &&
                     (document.activeElement == elt));
         } catch (e) {
-            // IE 9 bug (activeElement can't be accessed via IFRAME)
             return false;
         }
     },
@@ -159,32 +139,31 @@ var IMP_Autocompleter = Class.create({
     {
         try {
             this.input.focus();
-            this.box.addClassName(this.p.boxClassFocus);
+            this.box.classList.add(this.p.boxClassFocus);
         } catch (e) {
-            // IE8 bug (focus doesn't work on hidden fields)
-            this.focus.bind(this).defer();
+            setTimeout(this.focus.bind(this), 0);
         }
     },
 
     blur: function()
     {
-        this.box.removeClassName(this.p.boxClassFocus);
+        this.box.classList.remove(this.p.boxClassFocus);
     },
 
     reset: function()
     {
         this.data = [];
-        this.currentEntries().invoke('remove');
-        this.processValue($F(this.elt));
+        this.currentEntries().forEach(function(el) { el.remove(); });
+        this.processValue(this.elt.value);
         this.processInput();
         this.updateHiddenInput();
     },
 
     processInput: function()
     {
-        var tmp = $F(this.input);
+        var tmp = this.input.value;
 
-        if (!tmp.empty()) {
+        if (tmp !== '') {
             this.addNewItems([ new IMP_Autocompleter_Elt(tmp) ]);
             this.updateInput('');
         }
@@ -203,42 +182,49 @@ var IMP_Autocompleter = Class.create({
 
     getElts: function()
     {
-        return this.data.pluck('elt');
+        return this.data.map(function(v) { return v.elt; });
     },
 
     getEntryByElt: function(elt)
     {
-        return this.getEntryById(elt.retrieve('itemid'));
+        return this.getEntryById(elt._itemid);
     },
 
     getEntryById: function(id)
     {
-        return this.data.detect(function(v) {
-            return (v.id == id);
-        });
+        for (var i = 0; i < this.data.length; i++) {
+            if (this.data[i].id == id) {
+                return this.data[i];
+            }
+        }
+        return null;
     },
 
     addNewItems: function(value)
     {
         value = this.filterChoices(value);
 
-        if (!value.size()) {
+        if (!value.length) {
             return false;
         }
 
-        value.each(function(v) {
-            v.elt = new Element('LI', {
-                className: this.p.listClassItem,
-                title: v.label
-            });
+        value.forEach(function(v) {
+            v.elt = document.createElement('LI');
+            v.elt.className = this.p.listClassItem;
+            v.elt.title = v.label;
             v.id = ++this.itemid;
 
-            this.input.up('LI').insert({ before:
-                v.elt
-                    .insert((v.short_d || this.p.shortDisplayCallback(v.label)).truncate(this.p.maxItemSize).escapeHTML())
-                    .insert(this.deleteImg().clone(true).show())
-                    .store('itemid', v.id)
-            });
+            var displayText = (v.short_d || this.p.shortDisplayCallback(v.label));
+            if (displayText.length > this.p.maxItemSize) {
+                displayText = displayText.substring(0, this.p.maxItemSize) + '...';
+            }
+            v.elt.appendChild(document.createTextNode(displayText));
+            var delImg = this.deleteImg().cloneNode(true);
+            delImg.hidden = false;
+            v.elt.appendChild(delImg);
+            v.elt._itemid = v.id;
+
+            this.input.closest('LI').before(v.elt);
 
             this.data.push(v);
             this.p.onAdd(v);
@@ -248,7 +234,7 @@ var IMP_Autocompleter = Class.create({
         this.updateHiddenInput();
 
         if (this.knl) {
-            this.knl.hide();
+            this.knl.hide(); // eslint-disable-line horde/no-prototype-methods -- KeyNavList.hide()
         }
 
         return true;
@@ -256,29 +242,29 @@ var IMP_Autocompleter = Class.create({
 
     filterChoices: function(c)
     {
-        var cv = this.data.pluck('value');
+        var cv = this.data.map(function(v) { return v.value; });
 
-        return c.findAll(function(v) {
-            return !cv.include(v.value);
+        return c.filter(function(v) {
+            return cv.indexOf(v.value) === -1;
         });
     },
 
     currentEntries: function()
     {
-        return this.input.up('UL').select('LI.' + this.p.listClassItem);
+        return Array.from(this.input.closest('UL').querySelectorAll('LI.' + this.p.listClassItem));
     },
 
     updateInput: function(input)
     {
         var entry;
 
-        if (Object.isElement(input)) {
+        if (input instanceof HTMLElement) {
             entry = this.getEntryByElt(input);
-            this.input.setValue(entry.value);
+            this.input.value = entry.value;
             this.removeEntry(entry);
         } else {
-            if ($F(this.input) != input) {
-                this.input.setValue(input);
+            if (this.input.value != input) {
+                this.input.value = input;
                 this.resize();
             }
             this.focus();
@@ -292,7 +278,7 @@ var IMP_Autocompleter = Class.create({
         }
 
         entry.elt.remove();
-        this.data = this.data.findAll(function(v) {
+        this.data = this.data.filter(function(v) {
             return (v.id != entry.id);
         });
         this.updateHiddenInput();
@@ -303,28 +289,26 @@ var IMP_Autocompleter = Class.create({
     // AC Format: [ [ value, ID ], [ ... ], ... ]
     updateHiddenInput: function()
     {
-        var val = this.data.pluck('value').without('');
+        var val = this.data.map(function(v) { return v.value; }).filter(function(v) { return v !== ''; });
 
-        this.elt.setValue(val.join());
-        this.elt_ac.setValue(Object.toJSON(val.zip(this.data.pluck('id'))));
+        this.elt.value = val.join();
+        this.elt_ac.value = JSON.stringify(val.map(function(v, i) { return [v, this.data[i].id]; }, this));
     },
 
     resize: function()
     {
-        this.input.setStyle({
-            width: Math.max(80, $F(this.input).length * 9) + 'px'
-        });
+        this.input.style.width = Math.max(80, this.input.value.length * 9) + 'px';
         this.input.fire('AutoComplete:resize');
     },
 
     deleteImg: function()
     {
         if (!this.dimg) {
-            this.dimg = new Element('IMG', {
-                className: this.p.removeClass,
-                src: this.p.deleteIcon
-            }).hide();
-            this.box.insert(this.dimg);
+            this.dimg = document.createElement('IMG');
+            this.dimg.className = this.p.removeClass;
+            this.dimg.src = this.p.deleteIcon;
+            this.dimg.hidden = true;
+            this.box.appendChild(this.dimg);
         }
 
         return this.dimg;
@@ -334,11 +318,11 @@ var IMP_Autocompleter = Class.create({
 
     clickHandler: function(e)
     {
-        var elt = e.element(),
-            li = elt.up('LI');
+        var elt = e.target,
+            li = elt.closest('LI');
 
         if (!this.p.onEntryClick({ ac: this, elt: elt, entry: li })) {
-            if (elt.hasClassName(this.p.removeClass)) {
+            if (elt.classList.contains(this.p.removeClass)) {
                 this.removeEntry(this.getEntryByElt(li));
             }
         }
@@ -348,11 +332,11 @@ var IMP_Autocompleter = Class.create({
 
     dblclickHandler: function(e)
     {
-        var elt = e.findElement('LI');
+        var elt = e.target.closest('LI');
 
         this.processInput();
 
-        if (elt && elt.hasClassName(this.p.listClassItem)) {
+        if (elt && elt.classList.contains(this.p.listClassItem)) {
             this.updateInput(elt);
         } else {
             this.focus();
@@ -363,13 +347,16 @@ var IMP_Autocompleter = Class.create({
     {
         var tmp;
 
-        switch (e.which || e.keyCode || e.charCode) {
-        case Event.KEY_DELETE:
-        case Event.KEY_BACKSPACE:
-            if (!$F(this.input).length &&
-                (tmp = this.currentEntries().last())) {
-                this.updateInput(tmp);
-                e.stop();
+        switch (e.key) {
+        case 'Delete':
+        case 'Backspace':
+            if (!this.input.value.length) {
+                var entries = this.currentEntries();
+                tmp = entries.length ? entries[entries.length - 1] : null;
+                if (tmp) {
+                    this.updateInput(tmp);
+                    e.preventDefault();
+                }
             }
             break;
         }
@@ -377,15 +364,15 @@ var IMP_Autocompleter = Class.create({
 
     inputWatcher: function()
     {
-        var input = $F(this.input);
+        var input = this.input.value;
 
         if (input != this.lastinput) {
             this.processValue(input);
-            this.lastinput = $F(this.input);
+            this.lastinput = this.input.value;
             if (this.acTimeout) {
                 window.clearTimeout(this.acTimeout);
             }
-            this.acTimeout = this.doAutocomplete.bind(this, this.lastinput).delay(this.p.entryDelay);
+            this.acTimeout = setTimeout(this.doAutocomplete.bind(this, this.lastinput), this.p.entryDelay * 1000);
             this.resize();
         }
     },
@@ -396,29 +383,29 @@ var IMP_Autocompleter = Class.create({
             return;
         }
 
-        var c = this.cache.get(t), tmp;
+        var c = this.cache[t], tmp;
 
         if (c) {
             this.updateAutocomplete(t, c);
         } else if (t.length >= this.p.minChars) {
             tmp = this.p.onBeforeServerRequest(t, this.cache);
             if (tmp) {
-                this.cache.set(t, tmp);
+                this.cache[t] = tmp;
                 this.updateAutocomplete(t, tmp);
                 return;
             }
 
             this.initKnl();
             this.knl_status = 'loading';
-            this.knl.show([]);
+            this.knl.show([]); // eslint-disable-line horde/no-prototype-methods -- KeyNavList.show()
 
             ImpCore.doAction(
                 'autocompleteSearch',
-                Object.extend(this.p.autocompleterParams, { search: t }),
+                Object.assign(this.p.autocompleterParams, { search: t }),
                 {
                     callback: function(r, ajax) {
-                        this.cache.set(t, r.results);
-                        if (ajax.request.parameters.search == $F(this.input)) {
+                        this.cache[t] = r.results;
+                        if (ajax.request.parameters.search == this.input.value) {
                             this.updateAutocomplete(t, r.results);
                         }
                     }.bind(this)
@@ -440,28 +427,34 @@ var IMP_Autocompleter = Class.create({
             return;
         }
 
-        r.each(function(e) {
+        r.forEach(function(e) {
             var elt = new IMP_Autocompleter_Elt(e.v, e.l, e.s);
             this.p.onServerSuggestion(e, elt);
             obs.push(elt);
         }, this);
 
         obs = this.filterChoices(obs);
-        if (obs.size()) {
+        if (obs.length) {
             re = new RegExp(search, "i");
 
-            obs.each(function(o) {
+            obs.forEach(function(o) {
                 var l = o.label,
                     l2 = '';
 
-                (l.match(re) || []).each(function(m2) {
-                    var idx = l.indexOf(m2);
-                    l2 += l.substr(0, idx).escapeHTML() + "<strong>" + m2.escapeHTML() + "</strong>";
+                (l.match(re) || []).forEach(function(m2) {
+                    var idx = l.indexOf(m2),
+                        tmp = document.createElement('span');
+                    tmp.textContent = l.substr(0, idx);
+                    l2 += tmp.innerHTML + "<strong>";
+                    tmp.textContent = m2;
+                    l2 += tmp.innerHTML + "</strong>";
                     l = l.substr(idx + m2.length);
                 });
 
                 if (l.length) {
-                    l2 += l.escapeHTML();
+                    var tmp = document.createElement('span');
+                    tmp.textContent = l;
+                    l2 += tmp.innerHTML;
                 }
 
                 c.push({ l: l2, v: o });
@@ -473,7 +466,7 @@ var IMP_Autocompleter = Class.create({
         }
 
         this.initKnl();
-        this.knl.show(c);
+        this.knl.show(c); // eslint-disable-line horde/no-prototype-methods -- KeyNavList.show()
     },
 
     initKnl: function()
@@ -488,19 +481,17 @@ var IMP_Autocompleter = Class.create({
                 onShow: function(elt) {
                     switch (this.knl_status) {
                     case 'loading':
-                        elt.down().insert(
-                            new Element('LI').insert(
-                                this.p.loadingText.escapeHTML()
-                            ).addClassName(this.p.loadingTextClass)
-                        );
+                        var loadLi = document.createElement('LI');
+                        loadLi.textContent = this.p.loadingText;
+                        loadLi.className = this.p.loadingTextClass;
+                        elt.querySelector(':first-child').appendChild(loadLi);
                         break;
 
                     case 'noresults':
-                        elt.down().insert(
-                            new Element('LI').insert(
-                                this.p.noResultsText.escapeHTML()
-                            ).addClassName(this.p.noResultsTextClass)
-                        );
+                        var noLi = document.createElement('LI');
+                        noLi.textContent = this.p.noResultsText;
+                        noLi.className = this.p.noResultsTextClass;
+                        elt.querySelector(':first-child').appendChild(noLi);
                         break;
                     }
                 }.bind(this)
@@ -508,23 +499,12 @@ var IMP_Autocompleter = Class.create({
         }
     }
 
-}),
-
-IMP_Autocompleter_Elt = Class.create({
-
-    // elt,
-    // id,
-    // label,
-    // short_d,
-    // value,
+};
 
-    initialize: function(value, label, short_d)
-    {
-        this.value = value;
-        this.label = label || value;
-        if (short_d) {
-            this.short_d = short_d;
-        }
+var IMP_Autocompleter_Elt = function(value, label, short_d) {
+    this.value = value;
+    this.label = label || value;
+    if (short_d) {
+        this.short_d = short_d;
     }
-
-});
+};
diff --git a/js/contacts.js b/js/contacts.js
index 33a056b4b..f847c862b 100644
--- a/js/contacts.js
+++ b/js/contacts.js
@@ -14,38 +14,38 @@ var ImpContacts = {
 
     selectedAddresses: function()
     {
-        return $('selected_addresses').select('[value]');
+        return Array.from(document.getElementById('selected_addresses').querySelectorAll('[value]'));
     },
 
     addAddress: function(f)
     {
         var df = document.createDocumentFragment(),
             sa = this.selectedAddresses(),
-            sr = $('search_results'),
-            sel = $F(sr);
+            sr = document.getElementById('search_results'),
+            sel = Array.from(sr.selectedOptions).map(function(o) { return o.value; });
 
-        if (!sel.size()) {
+        if (!sel.length) {
             HordeCore.notify(this.text.select, 'horde.warning');
             return;
         }
 
-        sel.each(function(s) {
-            if (!sa.any(function(j) {
-                return (j.readAttribute('value') == s) &&
-                       (j.retrieve('header') == f);
+        sel.forEach(function(s) {
+            if (!sa.some(function(j) {
+                return (j.getAttribute('value') == s) &&
+                       (j._header == f);
             })) {
-                df.appendChild(
-                    new Element('OPTION', { value: s })
-                        .store('header', f)
-                        .insert(
-                            new Element('EM').insert(this.text.rcpt[f] + ': ')
-                        )
-                        .insert(s.escapeHTML())
-                );
+                var opt = document.createElement('OPTION');
+                opt.value = s;
+                opt._header = f;
+                var em = document.createElement('EM');
+                em.textContent = this.text.rcpt[f] + ': ';
+                opt.appendChild(em);
+                opt.appendChild(document.createTextNode(s));
+                df.appendChild(opt);
             }
         }, this);
 
-        $('selected_addresses').appendChild(df);
+        document.getElementById('selected_addresses').appendChild(df);
     },
 
     updateMessage: function()
@@ -59,19 +59,19 @@ var ImpContacts = {
             return;
         }
 
-        if (!sa.size()) {
+        if (!sa.length) {
             HordeCore.notify(this.text.no_contacts_selected, 'horde.warning');
             return;
         }
 
-        sa.each(function(s) {
-            var field = s.retrieve('header');
+        sa.forEach(function(s) {
+            var field = s._header;
 
-            if (Object.isUndefined(addr[field])) {
+            if (typeof addr[field] === 'undefined') {
                 addr[field] = [];
             }
 
-            addr[field].push(s.readAttribute('value'));
+            addr[field].push(s.getAttribute('value'));
         });
 
         $(parent.opener.document).fire('ImpContacts:update', addr);
@@ -80,7 +80,7 @@ var ImpContacts = {
 
     removeAddress: function()
     {
-        $('selected_addresses').childElements().each(function(o) {
+        Array.from(document.getElementById('selected_addresses').children).forEach(function(o) {
             if (o.selected) {
                 o.remove();
             }
@@ -89,21 +89,22 @@ var ImpContacts = {
 
     contactsSearch: function()
     {
-        var sr = $('search_results');
+        var sr = document.getElementById('search_results');
 
-        sr.select('[value]').invoke('remove');
-        sr.childElements().invoke('hide');
-        sr.appendChild(
-            new Element('OPTION', { disabled: true, value: "" })
-                .insert(this.text.searching)
-        );
+        Array.from(sr.querySelectorAll('[value]')).forEach(function(o) { o.remove(); });
+        Array.from(sr.children).forEach(function(o) { o.hidden = true; });
+        var opt = document.createElement('OPTION');
+        opt.disabled = true;
+        opt.value = "";
+        opt.textContent = this.text.searching;
+        sr.appendChild(opt);
 
         HordeCore.doAction('contactsSearch', {
-            search: this.searchGhost.hasinput ? $F('search') : '',
-            source: $F('source')
+            search: this.searchGhost.hasinput ? document.getElementById('search').value : '',
+            source: document.getElementById('source').value
         }, {
             callback: function(r) {
-                sr.select(':not([value])').invoke('show');
+                Array.from(sr.querySelectorAll(':not([value])')).forEach(function(o) { o.hidden = false; });
                 this.updateResults(r.results);
             }.bind(this)
         });
@@ -112,18 +113,18 @@ var ImpContacts = {
     updateResults: function(r)
     {
         var df = document.createDocumentFragment(),
-            sr = $('search_results');
+            sr = document.getElementById('search_results');
 
-        r.each(function(addr) {
-            df.appendChild(
-                new Element('OPTION', { value: addr })
-                    .insert(addr.escapeHTML())
-            );
+        r.forEach(function(addr) {
+            var opt = document.createElement('OPTION');
+            opt.value = addr;
+            opt.textContent = addr;
+            df.appendChild(opt);
         });
 
-        sr.select('[value]').invoke('remove');
+        Array.from(sr.querySelectorAll('[value]')).forEach(function(o) { o.remove(); });
 
-        if (r.size()) {
+        if (r.length) {
             sr.appendChild(df);
         }
     },
@@ -132,7 +133,7 @@ var ImpContacts = {
     {
         window.resizeBy(
             0,
-            Math.max(0, document.body.clientHeight - document.viewport.getHeight())
+            Math.max(0, document.body.clientHeight - document.documentElement.clientHeight)
         );
     },
 
@@ -141,7 +142,7 @@ var ImpContacts = {
         HordeCore.initHandler('click');
         HordeCore.initHandler('dblclick');
 
-        $('contacts').observe('FormGhost:submit', function(e) {
+        document.getElementById('contacts').addEventListener('FormGhost:submit', function(e) {
             if (this.searchGhost.hasinput) {
                 this.contactsSearch();
             }
@@ -154,12 +155,14 @@ var ImpContacts = {
 
         this.searchGhost = new FormGhost('search');
 
-        this.resize.bind(this).delay(0.1);
+        setTimeout(this.resize.bind(this), 100);
     },
 
     clickHandler: function(e)
     {
-        switch (e.element().readAttribute('id')) {
+        var id = e.target.id || (e.target.closest('[id]') || {}).id;
+
+        switch (id) {
         case 'btn_add_bcc':
             this.addAddress('bcc');
             break;
@@ -174,7 +177,7 @@ var ImpContacts = {
 
         case 'btn_cancel':
             window.close();
-            e.memo.hordecore_stop = true;
+            e.detail.hordecore_stop = true;
             break;
 
         case 'btn_clear':
@@ -186,7 +189,7 @@ var ImpContacts = {
             break;
 
         case 'btn_search_all':
-            $('search').value = '';
+            document.getElementById('search').value = '';
             this.contactsSearch();
             break;
 
@@ -198,7 +201,9 @@ var ImpContacts = {
 
     dblclickHandler: function(e)
     {
-        switch (e.element().readAttribute('id')) {
+        var id = e.target.id || (e.target.closest('[id]') || {}).id;
+
+        switch (id) {
         case 'search_results':
             this.addAddress('to');
             break;
@@ -211,6 +216,6 @@ var ImpContacts = {
 
 };
 
-document.observe('dom:loaded', ImpContacts.onDomLoad.bind(ImpContacts));
-document.observe('HordeCore:click', ImpContacts.clickHandler.bindAsEventListener(ImpContacts));
-document.observe('HordeCore:dblclick', ImpContacts.dblclickHandler.bindAsEventListener(ImpContacts));
+document.addEventListener('DOMContentLoaded', ImpContacts.onDomLoad.bind(ImpContacts));
+document.addEventListener('HordeCore:click', ImpContacts.clickHandler.bind(ImpContacts));
+document.addEventListener('HordeCore:dblclick', ImpContacts.dblclickHandler.bind(ImpContacts));
diff --git a/js/draghandler.js b/js/draghandler.js
index 48c9728bf..bcf5e5a91 100644
--- a/js/draghandler.js
+++ b/js/draghandler.js
@@ -1,5 +1,5 @@
 /**
- * DragHandler library for use with prototypejs.
+ * DragHandler library.
  *
  * @author     Michael Slusarz <slusarz@horde.org>
  * @copyright  2013-2015 Horde LLC
@@ -19,7 +19,7 @@ var DragHandler = {
     {
         return (e.dataTransfer &&
                 e.dataTransfer.types &&
-                $A(e.dataTransfer.types).include('Files') &&
+                Array.from(e.dataTransfer.types).indexOf('Files') !== -1 &&
                 ((e.type != 'drop') || e.dataTransfer.files.length));
     },
 
@@ -27,25 +27,20 @@ var DragHandler = {
     {
         if (this.dropelt &&
             (e.dataTransfer ||
-             (e.memo && e.memo.dataTransfer) ||
-             this.dropelt.visible())) {
-            if (Prototype.Browser.IE &&
-                !(("onpropertychange" in document) && (!!window.matchMedia))) {
-                // IE 9 supports drag/drop, but not dataTransfer.files
-            } else {
-                switch (e.type) {
-                case 'dragleave':
-                    this.handleLeave();
-                    break;
-
-                case 'dragover':
-                    this.handleOver(e);
-                    break;
-
-                case 'drop':
-                    this.handleDrop(e);
-                    break;
-                }
+             (e.detail && e.detail.dataTransfer) ||
+             !this.dropelt.hidden)) {
+            switch (e.type) {
+            case 'dragleave':
+                this.handleLeave();
+                break;
+
+            case 'dragover':
+                this.handleOver(e);
+                break;
+
+            case 'drop':
+                this.handleDrop(e);
+                break;
             }
         }
     },
@@ -53,23 +48,23 @@ var DragHandler = {
     handleDrop: function(e)
     {
         this.leave = true;
-        this.hide();
+        this.hide(); // eslint-disable-line horde/no-prototype-methods -- DragHandler.hide()
 
         if (this.isFileDrag(e)) {
-            if (this.dropelt.hasClassName(this.hoverclass)) {
+            if (this.dropelt.classList.contains(this.hoverclass)) {
                 this.dropelt.fire('DragHandler:drop', e.dataTransfer.files);
             }
-            e.stop();
-        } else if (!e.findElement('TEXTAREA') && !e.findElement('INPUT')) {
-            e.stop();
+            e.preventDefault();
+        } else if (!e.target.closest('TEXTAREA') && !e.target.closest('INPUT')) {
+            e.preventDefault();
         }
     },
 
     hide: function()
     {
         if (this.leave) {
-            this.dropelt.hide();
-            this.droptarget.show();
+            this.dropelt.hidden = true;
+            this.droptarget.hidden = false;
             this.leave = false;
         }
     },
@@ -77,7 +72,7 @@ var DragHandler = {
     handleLeave: function()
     {
         clearTimeout(this.to);
-        this.to = this.hide.bind(this).delay(0.25);
+        this.to = setTimeout(this.hide.bind(this), 250);
         this.leave = true;
     },
 
@@ -85,27 +80,30 @@ var DragHandler = {
     {
         var file = this.isFileDrag(e);
 
-        if (file && !this.dropelt.visible()) {
-            this.dropelt.clonePosition(this.droptarget).show();
-            this.droptarget.hide();
+        if (file && this.dropelt.hidden) {
+            // Position dropelt over droptarget
+            var rect = this.droptarget.getBoundingClientRect();
+            this.dropelt.style.position = 'absolute';
+            this.dropelt.style.left = rect.left + 'px';
+            this.dropelt.style.top = rect.top + 'px';
+            this.dropelt.style.width = rect.width + 'px';
+            this.dropelt.style.height = rect.height + 'px';
+            this.dropelt.hidden = false;
+            this.droptarget.hidden = true;
         }
 
         this.leave = false;
 
         if (file && (e.target == this.dropelt)) {
-            this.dropelt.addClassName(this.hoverclass);
-            e.stop();
+            this.dropelt.classList.add(this.hoverclass);
+            e.preventDefault();
         } else {
-            this.dropelt.removeClassName(this.hoverclass);
-            if (Prototype.Browser.IE ||
-                Prototype.Browser.Gecko) {
-                e.stop();
-            }
+            this.dropelt.classList.remove(this.hoverclass);
         }
     }
 
 };
 
-document.observe('dragleave', DragHandler.handleObserve.bindAsEventListener(DragHandler));
-document.observe('dragover', DragHandler.handleObserve.bindAsEventListener(DragHandler));
-document.observe('drop', DragHandler.handleObserve.bindAsEventListener(DragHandler));
+document.addEventListener('dragleave', DragHandler.handleObserve.bind(DragHandler));
+document.addEventListener('dragover', DragHandler.handleObserve.bind(DragHandler));
+document.addEventListener('drop', DragHandler.handleObserve.bind(DragHandler));
diff --git a/js/editor.js b/js/editor.js
index 1da4c8593..5a365d532 100644
--- a/js/editor.js
+++ b/js/editor.js
@@ -6,43 +6,36 @@
  * @license    GPL-2 (http://www.horde.org/licenses/gpl)
  */
 
-var IMP_Editor = Class.create({
+var IMP_Editor = function(id, config) {
+    this.config = Object.assign({}, config);
+    this.id = id;
 
-    // config,
-    // dready,
-    // editor,
-    // id,
-    // iready
-    // wait,
+    this.start();
 
-    initialize: function(id, config)
-    {
-        this.config = Object.clone(config);
-        this.id = id;
-
-        this.start();
+    this.editor.on('instanceReady', function(evt) {
+        this.iready = true;
+        document.fire('IMP_Editor:ready', evt.editor);
+    }.bind(this));
+    this.editor.on('dataReady', function(evt) {
+        if (!this.dready) {
+            document.fire('IMP_Editor:dataReady', evt.editor);
+            this.dready = true;
+        }
+    }.bind(this));
+    this.editor.on('instanceDestroyed', function(evt) {
+        this.dready = this.iready = this.editor = false;
+        document.fire('IMP_Editor:destroy', evt.editor);
+    }.bind(this));
+};
 
-        this.editor.on('instanceReady', function(evt) {
-            this.iready = true;
-            document.fire('IMP_Editor:ready', evt.editor);
-        }.bind(this));
-        this.editor.on('dataReady', function(evt) {
-            if (!this.dready) {
-                document.fire('IMP_Editor:dataReady', evt.editor);
-                this.dready = true;
-            }
-        }.bind(this));
-        this.editor.on('instanceDestroyed', function(evt) {
-            this.dready = this.iready = this.editor = false;
-            document.fire('IMP_Editor:destroy', evt.editor);
-        }.bind(this));
-    },
+IMP_Editor.prototype = {
 
     start: function()
     {
         if (!this.editor) {
-            if (Object.isUndefined(this.config.height)) {
-                this.config.height = Math.max($(this.id).getHeight(), 200) - 75;
+            if (typeof this.config.height === 'undefined') {
+                var elt = document.getElementById(this.id);
+                this.config.height = Math.max(elt.offsetHeight, 200) - 75;
             }
             this.editor = CKEDITOR.replace(this.id, this.config);
         }
@@ -68,7 +61,7 @@ var IMP_Editor = Class.create({
     setData: function(data)
     {
         if (this.busy()) {
-            this.setData.bind(this, data).delay(0.1);
+            setTimeout(this.setData.bind(this, data), 100);
         } else {
             this.wait = true;
             this.editor.setData(data, function() {
@@ -80,7 +73,7 @@ var IMP_Editor = Class.create({
     resize: function(width, height)
     {
         if (this.busy()) {
-            this.resize.bind(this, width, height).delay(0.1);
+            setTimeout(this.resize.bind(this, width, height), 100);
         } else {
             this.editor.resize(width, height);
         }
@@ -89,7 +82,7 @@ var IMP_Editor = Class.create({
     focus: function()
     {
         if (this.busy()) {
-            this.focus.bind(this).delay(0.1);
+            setTimeout(this.focus.bind(this), 100);
         } else {
             this.editor.focus();
         }
@@ -98,10 +91,10 @@ var IMP_Editor = Class.create({
     updateElement: function()
     {
         if (this.busy()) {
-            this.updateElement.bind(this).delay(0.1);
+            setTimeout(this.updateElement.bind(this), 100);
         } else {
             this.editor.updateElement();
         }
     }
 
-});
+};
diff --git a/js/imp.js b/js/imp.js
index a9caa40fa..f856506a1 100644
--- a/js/imp.js
+++ b/js/imp.js
@@ -19,42 +19,40 @@ var IMP_JS = {
     unblockImages: function(e)
     {
         var a, callback, doc,
-            elt = e.element(),
-            box = elt.up('.mimeStatusMessageTable').up(),
-            iframe = elt.up('.mimePartBase').down('.mimePartData IFRAME.htmlMsgData');
+            elt = e.target,
+            box = elt.closest('.mimeStatusMessageTable').parentElement,
+            iframe = elt.closest('.mimePartBase').querySelector('.mimePartData IFRAME.htmlMsgData');
 
-        e.stop();
+        e.preventDefault();
 
-        if (elt.readAttribute('noUnblockImageAdd')) {
-            box.slideUp({
-                afterFinish: function() { box.remove(); },
-                duration: 0.6
-            });
+        if (elt.getAttribute('noUnblockImageAdd')) {
+            box.hidden = true;
+            box.remove();
         } else {
-            a = new Element('A')
-                .insert(IMP_JS.unblock_image_text)
-                .observe('click', function() {
-                    HordeCore.doAction('imageUnblockAdd', {
-                        muid: elt.readAttribute('muid')
-                    });
-
-                    box.slideUp({
-                        afterFinish: function() { box.remove(); },
-                        duration: 0.6
-                    });
+            a = document.createElement('A');
+            a.textContent = IMP_JS.unblock_image_text;
+            a.addEventListener('click', function() {
+                HordeCore.doAction('imageUnblockAdd', {
+                    muid: elt.getAttribute('muid')
                 });
 
-            elt.up('TBODY').update(
-                new Element('TR').insert(
-                    new Element('TD').insert(a)
-                )
-            );
+                box.hidden = true;
+                box.remove();
+            });
+
+            var tbody = elt.closest('TBODY');
+            var tr = document.createElement('TR');
+            var td = document.createElement('TD');
+            td.appendChild(a);
+            tr.appendChild(td);
+            tbody.innerHTML = '';
+            tbody.appendChild(tr);
         }
 
         callback = this.iframeResize.bind(this, iframe);
         doc = this.iframeDoc(iframe);
 
-        Prototype.Selector.select('[htmlimgblocked]', doc).each(function(img) {
+        doc.querySelectorAll('[htmlimgblocked]').forEach(function(img) {
             var src = img.getAttribute('htmlimgblocked');
             img.removeAttribute('htmlimgblocked');
 
@@ -69,24 +67,23 @@ var IMP_JS = {
                     if (img.style.setProperty) {
                         img.style.setProperty('background-image', 'url(' + src + ')', '');
                     } else {
-                        // IE workaround
                         img.style.backgroundImage = 'url(' + src + ')';
                     }
                 }
             }
-        }, this);
+        });
 
-        Prototype.Selector.select('[htmlimgblocked_srcset]', doc).each(function(img) {
+        doc.querySelectorAll('[htmlimgblocked_srcset]').forEach(function(img) {
             img.setAttribute('srcset', img.getAttribute('htmlimgblocked_srcset'));
             img.removeAttribute('htmlimgblocked_srcset');
         });
 
-        Prototype.Selector.select('[htmlcssblocked]', doc).each(function(link) {
+        doc.querySelectorAll('[htmlcssblocked]').forEach(function(link) {
             link.setAttribute('href', link.getAttribute('htmlcssblocked'));
             link.removeAttribute('htmlcssblocked');
         });
 
-        Prototype.Selector.select('STYLE[type="text/x-imp-cssblocked"]', doc).each(function(style) {
+        doc.querySelectorAll('STYLE[type="text/x-imp-cssblocked"]').forEach(function(style) {
             style.setAttribute('type', 'text/css');
         });
 
@@ -95,7 +92,10 @@ var IMP_JS = {
 
     iframeInject: function(id, data)
     {
-        if (!(id = $(id))) {
+        if (typeof id === 'string') {
+            id = document.getElementById(id);
+        }
+        if (!id) {
             return;
         }
 
@@ -111,31 +111,27 @@ var IMP_JS = {
         d.close();
 
         ev = function(name, e) {
-            id.fire('IMP_JS:' + name, e);
+            $(id).fire('IMP_JS:' + name, e);
         };
 
-        if (d.addEventListener) {
-            d.addEventListener('click', ev.curry('htmliframe_click'), false);
-            d.addEventListener('keydown', ev.curry('htmliframe_keydown'), false);
-        } else {
-            d.attachEvent('onclick', ev.curry('htmliframe_click'));
-            d.attachEvent('onkeydown', ev.curry('htmliframe_keydown'));
-        }
+        d.addEventListener('click', ev.bind(null, 'htmliframe_click'), false);
+        d.addEventListener('keydown', ev.bind(null, 'htmliframe_keydown'), false);
 
         this.iframeOverflowY(id, false);
-        id.show().previous().remove();
+        id.hidden = false;
+        var prev = id.previousElementSibling;
+        if (prev) { prev.remove(); }
         this.iframeResize(id);
     },
 
     // iframe = (Element)
     iframeResize: function(iframe)
     {
-        var id = iframe.identify();
+        var id = iframe.id || (iframe.id = 'horde_' + Date.now());
 
-        // IE (at a minimum) needs a slight delay to size properly
         if (!this.iframeresize_run[id]) {
             this.iframeresize_run[id] = true;
-            this.iframeResizeRun.bind(this, iframe).delay(this.resize_delay);
+            setTimeout(this.iframeResizeRun.bind(this, iframe), this.resize_delay * 1000);
         }
     },
 
@@ -145,7 +141,8 @@ var IMP_JS = {
             doc = this.iframeDoc(id);
 
         if (!doc) {
-            this.iframeresize_run[id.identify()] = false;
+            var eid = id.id || (id.id = 'horde_' + Date.now());
+            this.iframeresize_run[eid] = false;
             return;
         }
 
@@ -154,36 +151,35 @@ var IMP_JS = {
         iHeight = function() {
             return Math.max(
                 body.offsetHeight,
-                // IE 8 only
-                (Prototype.Browser.IE && !document.addEventListener) ? body.scrollHeight : 0,
                 html.offsetHeight,
                 html.scrollHeight
             );
         };
 
-        Element.setStyle(body, { height: null });
+        body.style.height = '';
 
         h1 = iHeight();
-        id.setStyle({ height: h1 + 'px' });
+        id.style.height = h1 + 'px';
 
         h2 = iHeight();
         if (h2 > h1) {
-            id.setStyle({ height: h2 + 'px' });
+            id.style.height = h2 + 'px';
         }
 
         this.iframeImgLazyLoad(id);
 
-        this.iframeresize_run[id.identify()] = false;
+        var eid2 = id.id || (id.id = 'horde_' + Date.now());
+        this.iframeresize_run[eid2] = false;
     },
 
     iframeImgLazyLoad: function(iframe)
     {
-        var id = iframe.identify();
+        var id = iframe.id || (iframe.id = 'horde_' + Date.now());
 
         if (!this.lazyload_run[id]) {
             this.lazyload_run[id] = true;
-            this.iframeImgLazyLoadRun.bind(this, iframe)
-                .delay(this.resize_delay);
+            setTimeout(this.iframeImgLazyLoadRun.bind(this, iframe),
+                this.resize_delay * 1000);
         }
     },
 
@@ -194,19 +190,22 @@ var IMP_JS = {
             mb = this.messageBody();
 
         if (!doc) {
-            this.lazyload_run[iframe.identify()] = false;
+            var eid = iframe.id || (iframe.id = 'horde_' + Date.now());
+            this.lazyload_run[eid] = false;
             return;
         }
 
         /* Load messages within 1 scrolled page of range boundaries. */
-        mb_height = mb.getHeight();
+        mb_height = mb.offsetHeight;
         range_top = mb.scrollTop - mb_height;
         range_bottom = mb.scrollTop + (2 * mb_height);
 
-        imgs = Prototype.Selector.select('IMG[data-src]', doc).findAll(Element.visible);
+        imgs = Array.from(doc.querySelectorAll('IMG[data-src]')).filter(function(img) {
+            return !img.hidden && img.offsetWidth > 0;
+        });
 
-        if (imgs.size()) {
-            iframe.setStyle({ overflowY: 'hidden' });
+        if (imgs.length) {
+            iframe.style.overflowY = 'hidden';
 
             error = this.iframeOverflowY.bind(this, iframe);
             resize = function() {
@@ -214,19 +213,21 @@ var IMP_JS = {
                 this.iframeOverflowY(iframe, true);
             }.bind(this);
 
-            imgs.each(function(img) {
-                var co = Element.cumulativeOffset(img);
-                if (co.top > range_top && co.top < range_bottom) {
+            imgs.forEach(function(img) {
+                var rect = img.getBoundingClientRect();
+                var co_top = rect.top + (doc.defaultView ? doc.defaultView.pageYOffset : 0);
+                if (co_top > range_top && co_top < range_bottom) {
                     this.iframeOverflowY(iframe, false);
                     img.onerror = error;
                     img.onload = resize;
-                    Element.writeAttribute(img, 'src', Element.readAttribute(img, 'data-src'));
-                    Element.writeAttribute(img, 'data-src', null);
+                    img.setAttribute('src', img.getAttribute('data-src'));
+                    img.removeAttribute('data-src');
                 }
             }, this);
         }
 
-        this.lazyload_run[iframe.identify()] = false;
+        var eid2 = iframe.id || (iframe.id = 'horde_' + Date.now());
+        this.lazyload_run[eid2] = false;
     },
 
     iframeDoc: function(i)
@@ -237,18 +238,18 @@ var IMP_JS = {
 
     iframeOverflowY: function(id, show)
     {
-        var key = id.identify();
+        var key = id.id || (id.id = 'horde_' + Date.now());
 
         if (show) {
             if (this.iframe_y[key] && !(--this.iframe_y[key])) {
-                id.setStyle({ overflowY: '' });
+                id.style.overflowY = '';
                 delete this.iframe_y[key];
             }
         } else {
             if (this.iframe_y[key]) {
                 ++this.iframe_y[key];
             } else {
-                id.setStyle({ overflowY: 'hidden' });
+                id.style.overflowY = 'hidden';
                 this.iframe_y[key] = 1;
             }
         }
@@ -256,14 +257,14 @@ var IMP_JS = {
 
     messageBody: function()
     {
-        return $('previewPane') || $('messageBody');
+        return document.getElementById('previewPane') || document.getElementById('messageBody');
     },
 
     printWindow: function(win)
     {
         win.print();
         // Bug #12833: Fixes closing print window in Chrome.
-        (function() { win.close(); }).defer();
+        setTimeout(function() { win.close(); }, 0);
     },
 
     resizePopup: function(win)
@@ -304,12 +305,12 @@ var IMP_JS = {
         var mb = this.messageBody();
 
         if (mb) {
-            mb.observe('scroll', function() {
-                $('messageBody').select('IFRAME.htmlMsgData').each(this.iframeImgLazyLoad.bind(this));
+            mb.addEventListener('scroll', function() {
+                Array.from(document.getElementById('messageBody').querySelectorAll('IFRAME.htmlMsgData')).forEach(this.iframeImgLazyLoad.bind(this));
             }.bind(this));
         }
     }
 
 };
 
-document.observe('dom:loaded', IMP_JS.onDomLoad.bind(IMP_JS));
+document.addEventListener('DOMContentLoaded', IMP_JS.onDomLoad.bind(IMP_JS));
diff --git a/js/login.js b/js/login.js
index a9f91f20f..25ac10692 100644
--- a/js/login.js
+++ b/js/login.js
@@ -6,12 +6,15 @@
  * @license    GPL-2 (http://www.horde.org/licenses/gpl)
  */
 
-HordeLogin.submit = HordeLogin.submit.wrap(function(parentfunc) {
-    var k = $('imp_server_key');
-    if (k && $F(k).startsWith('_')) {
-        alert(HordeLogin.server_key_error);
-        k.focus();
-    } else {
-        parentfunc();
-    }
-});
+(function() {
+    var origSubmit = HordeLogin.submit;
+    HordeLogin.submit = function() {
+        var k = document.getElementById('imp_server_key');
+        if (k && k.value.startsWith('_')) {
+            alert(HordeLogin.server_key_error);
+            k.focus();
+        } else {
+            origSubmit.call(HordeLogin);
+        }
+    };
+})();
diff --git a/js/maillog.js b/js/maillog.js
index bc543afcd..fff1fe899 100644
--- a/js/maillog.js
+++ b/js/maillog.js
@@ -19,11 +19,13 @@ var ImpMaillog = {
             base.HordeCore.notify(this.error_msg, 'horde.error');
             window.close();
         } else {
-            document.body.insert(this.error_msg.escapeHTML());
+            var tmp = document.createElement('SPAN');
+            tmp.textContent = this.error_msg;
+            document.body.appendChild(tmp);
         }
     }
 
 };
 
 /* Initialize onload handler. */
-document.observe('dom:loaded', ImpMaillog.onDomLoad.bind(ImpMaillog));
+document.addEventListener('DOMContentLoaded', ImpMaillog.onDomLoad.bind(ImpMaillog));
diff --git a/js/message.js b/js/message.js
index a7ff3c52e..64c04e75f 100644
--- a/js/message.js
+++ b/js/message.js
@@ -22,8 +22,8 @@ var ImpMessage = {
         case 'reply_all':
         case 'reply_auto':
         case 'reply_list':
-            $('compose').show();
-            $('redirect').hide();
+            document.getElementById('compose').hidden = false;
+            document.getElementById('redirect').hidden = true;
             func = 'getReplyData';
             break;
 
@@ -31,30 +31,30 @@ var ImpMessage = {
         case 'forward_attach':
         case 'forward_body':
         case 'forward_both':
-            $('compose').show();
-            $('redirect').hide();
+            document.getElementById('compose').hidden = false;
+            document.getElementById('redirect').hidden = true;
             func = 'getForwardData';
             break;
 
         case 'forward_editasnew':
-            $('compose').show();
-            $('redirect').hide();
+            document.getElementById('compose').hidden = false;
+            document.getElementById('redirect').hidden = true;
             func = 'getResumeData';
             type = 'editasnew';
             break;
 
         case 'forward_redirect':
-            $('compose').hide();
-            $('redirect').show();
+            document.getElementById('compose').hidden = true;
+            document.getElementById('redirect').hidden = false;
             func = 'getRedirectData';
             break;
         }
 
-        $('msgData').hide();
-        $('qreply').show();
+        document.getElementById('msgData').hidden = true;
+        document.getElementById('qreply').hidden = false;
 
         ImpCore.doAction(func, {
-            imp_compose: $F('composeCache'),
+            imp_compose: document.getElementById('composeCache').value,
             type: type,
             view: this.mbox
         }, {
@@ -65,8 +65,9 @@ var ImpMessage = {
 
     updateAddressHeader: function(e)
     {
+        var tr = e.target.closest('TR');
         ImpCore.doAction('addressHeader', {
-            header: e.element().up('TR').identify().substring(9).toLowerCase(),
+            header: tr.id.substring(9).toLowerCase(),
             view: this.mbox
         }, {
             callback: this._updateAddressHeaderCallback.bind(this),
@@ -76,19 +77,20 @@ var ImpMessage = {
 
     _updateAddressHeaderCallback: function(r)
     {
-        $H(r.hdr_data).each(function(d) {
-            this.updateHeader(d.key, d.value);
+        Object.entries(r.hdr_data).forEach(function(d) {
+            this.updateHeader(d[0], d[1]);
         }, this);
     },
 
     updateHeader: function(hdr, data, limit)
     {
-        var elt = $('msgHeader' + hdr.capitalize());
+        var elt = document.getElementById('msgHeader' + hdr.charAt(0).toUpperCase() + hdr.slice(1));
         if (elt) {
-            elt = elt.show().down('TD:last');
-            ImpCore.buildAddressLinks(data, elt, limit);
+            elt.hidden = false;
+            var td = elt.querySelector('TD:last-child');
+            ImpCore.buildAddressLinks(data, td, limit);
             if (hdr === 'from' && this.resent) {
-                ImpCore.buildResentHeader(elt, this.resent);
+                ImpCore.buildResentHeader(td, this.resent);
                 delete this.resent;
             }
         }
@@ -96,14 +98,14 @@ var ImpMessage = {
 
     reloadPart: function(mimeid, params)
     {
-        ImpCore.doAction('inlineMessageOutput', Object.extend(params, {
+        ImpCore.doAction('inlineMessageOutput', Object.assign(params, {
             mimeid: mimeid,
             view: this.mbox
         }), {
             callback: function(r) {
-                $('messageBody')
-                    .down('DIV[impcontentsmimeid="' + r.mimeid + '"]')
-                    .replace(r.text);
+                var target = document.getElementById('messageBody')
+                    .querySelector('DIV[impcontentsmimeid="' + r.mimeid + '"]');
+                target.outerHTML = r.text;
             },
             uids: [ this.buid ]
         });
@@ -112,22 +114,23 @@ var ImpMessage = {
     /* Click handlers. */
     clickHandler: function(e)
     {
-        var base, cnames;
+        var base, cnames,
+            id = e.target.id || (e.target.closest('[id]') || {}).id;
 
-        switch (e.element().readAttribute('id')) {
+        switch (id) {
         case 'windowclose':
             window.close();
-            e.memo.hordecore_stop = true;
+            e.detail.hordecore_stop = true;
             break;
 
         case 'forward_link':
             this.quickreply('forward_auto');
-            e.memo.stop();
+            e.detail.stop();
             break;
 
         case 'reply_link':
             this.quickreply('reply_auto');
-            e.memo.stop();
+            e.detail.stop();
             break;
 
         case 'button_delete':
@@ -135,19 +138,19 @@ var ImpMessage = {
         case 'button_spam':
             if ((base = ImpCore.baseAvailable())) {
                 base.focus();
-                if (e.element().identify() == 'button_delete') {
+                if (id == 'button_delete') {
                     base.ImpBase.deleteMsg({
                         mailbox: this.mbox,
                         uid: this.buid
                     });
                 } else {
-                    base.ImpBase.reportSpam(e.element().identify() == 'button_spam', {
+                    base.ImpBase.reportSpam(id == 'button_spam', {
                         mailbox: this.mbox,
                         uid: this.buid
                     });
                 }
             } else {
-                if (e.element().identify() == 'button_delete') {
+                if (id == 'button_delete') {
                     ImpCore.doAction('deleteMessages', {
                         view: this.mbox
                     }, {
@@ -156,7 +159,7 @@ var ImpMessage = {
                     });
                 } else {
                     ImpCore.doAction('reportSpam', {
-                        spam: ~~(e.element().identify() == 'button_spam'),
+                        spam: ~~(id == 'button_spam'),
                         view: this.mbox
                     }, {
                         uids: [ this.buid ],
@@ -165,7 +168,7 @@ var ImpMessage = {
                 }
             }
             window.close();
-            e.memo.hordecore_stop = true;
+            e.detail.hordecore_stop = true;
             break;
 
         case 'msg_view_source':
@@ -189,7 +192,7 @@ var ImpMessage = {
             break;
 
         case 'qreply':
-            if (e.memo.element().match('DIV.headercloseimg IMG')) {
+            if (e.detail.element().match('DIV.headercloseimg IMG')) {
                 ImpCompose.confirmCancel();
             }
             break;
@@ -199,37 +202,40 @@ var ImpMessage = {
                 view: this.mbox
             }, {
                 callback: function(r) {
-                    $('sendMdnMessage').up(1).fade({ duration: 0.2 });
+                    var msg = document.getElementById('sendMdnMessage');
+                    if (msg) {
+                        msg.parentElement.hidden = true;
+                    }
                 },
                 uids: [ this.buid ]
             });
-            e.memo.stop();
+            e.detail.stop();
             break;
 
         default:
-            cnames = $w(e.element().className);
+            cnames = (e.target.className || '').split(/\s+/);
 
             if (cnames.indexOf('printAtc') !== -1) {
                 HordeCore.popupWindow(ImpCore.conf.URI_VIEW, {
                     actionID: 'print_attach',
                     buid: this.buid,
-                    id: e.element().readAttribute('mimeid'),
+                    id: e.target.getAttribute('mimeid'),
                     mailbox: this.mbox
                 }, {
                     name: this.buid + '|' + this.mbox + '|print',
                     onload: IMP_JS.printWindow
                 });
-                e.memo.stop();
+                e.detail.stop();
             } else if (cnames.indexOf('stripAtc') !== -1) {
                 if (window.confirm(ImpCore.text.strip_warn)) {
                     ImpCore.reloadMessage({
                         actionID: 'strip_attachment',
                         buid: this.buid,
-                        id: e.element().readAttribute('mimeid'),
+                        id: e.target.getAttribute('mimeid'),
                         mailbox: this.mbox
                     });
                 }
-                e.memo.stop();
+                e.detail.stop();
             }
             break;
         }
@@ -237,7 +243,7 @@ var ImpMessage = {
 
     contextOnClick: function(e)
     {
-        var id = e.memo.elt.readAttribute('id');
+        var id = e.detail.elt.id;
 
         switch (id) {
         case 'ctx_reply_reply':
@@ -258,24 +264,25 @@ var ImpMessage = {
 
     resizeWindow: function()
     {
-        var mb = $('msgData').down('DIV.messageBody');
-
-        mb.setStyle({
-            height: Math.max(
-                        document.viewport.getHeight() -
-                            mb.cumulativeOffset()[1] -
-                            parseInt(mb.getStyle('paddingTop'), 10) -
-                            parseInt(mb.getStyle('paddingBottom'), 10),
+        var mb = document.getElementById('msgData').querySelector('DIV.messageBody');
+
+        mb.style.height = Math.max(
+                        document.documentElement.clientHeight -
+                            mb.getBoundingClientRect().top -
+                            parseInt(window.getComputedStyle(mb).paddingTop, 10) -
+                            parseInt(window.getComputedStyle(mb).paddingBottom, 10),
                          0
-                    ) + 'px'
-        });
+                    ) + 'px';
     },
 
     _mimeTreeCallback: function(r)
     {
-        $('msg_all_parts').up().hide();
+        var allParts = document.getElementById('msg_all_parts');
+        if (allParts) { allParts.parentElement.hidden = true; }
 
-        $('partlist').show().update(r.tree);
+        var partlist = document.getElementById('partlist');
+        partlist.hidden = false;
+        partlist.innerHTML = r.tree;
 
         this.resizeWindow();
     },
@@ -287,7 +294,13 @@ var ImpMessage = {
         HordeCore.initHandler('click');
 
         if (ImpCore.conf.disable_compose) {
-            $('reply_link', 'forward_link').compact().invoke('up', 'SPAN').invoke('remove');
+            ['reply_link', 'forward_link'].forEach(function(id) {
+                var elt = document.getElementById(id);
+                if (elt) {
+                    var span = elt.closest('SPAN');
+                    if (span) { span.remove(); }
+                }
+            });
             delete ImpCore.context.ctx_contacts['new'];
         } else {
             ImpCore.addPopdown('reply_link', 'reply');
@@ -298,7 +311,7 @@ var ImpMessage = {
         }
 
         /* Set up address linking. */
-        [ 'from', 'to', 'cc', 'bcc' ].each(function(a) {
+        [ 'from', 'to', 'cc', 'bcc' ].forEach(function(a) {
             if (this[a]) {
                 this.updateHeader(a, this[a], true);
                 delete this[a];
@@ -310,7 +323,7 @@ var ImpMessage = {
                 base.ImpBase.poll();
             } else if (this.tasks) {
                 if (this.tasks['imp:maillog']) {
-                    this.tasks['imp:maillog'].each(function(l) {
+                    this.tasks['imp:maillog'].forEach(function(l) {
                         if (this.mbox == l.mbox &&
                             this.buid == l.buid) {
                             ImpCore.updateMsgLog(l.log);
@@ -328,8 +341,8 @@ var ImpMessage = {
         ImpCore.updateAtcList(this.msg_atc);
         delete this.msg_atc;
 
-        $('impLoading').hide();
-        $('msgData').show();
+        document.getElementById('impLoading').hidden = true;
+        document.getElementById('msgData').hidden = false;
 
         this.resizeWindow();
     }
@@ -338,29 +351,17 @@ var ImpMessage = {
 
 /* Attach event handlers. */
 /* Initialize onload handler. */
-document.observe('dom:loaded', function() {
-    if (Prototype.Browser.IE && !document.addEventListener) {
-        // IE 8
-        IMP_JS.iframeResize = IMP_JS.iframeResize.wrap(function(parentfunc, e, id) {
-            if ($('msgData').visible()) {
-                (function() { parentfunc(e, id); }).defer();
-            } else {
-                IMP_JS.iframeResize.bind(IMP_JS, e, id).defer();
-            }
-        });
-        ImpMessage.onDomLoad.bind(ImpMessage).delay(0.1);
-    } else {
-        ImpMessage.onDomLoad();
-    }
+document.addEventListener('DOMContentLoaded', function() {
+    ImpMessage.onDomLoad();
 });
-document.observe('HordeCore:click', ImpMessage.clickHandler.bindAsEventListener(ImpMessage));
-Event.observe(window, 'resize', ImpMessage.resizeWindow.bind(ImpMessage));
+document.addEventListener('HordeCore:click', ImpMessage.clickHandler.bind(ImpMessage));
+window.addEventListener('resize', ImpMessage.resizeWindow.bind(ImpMessage));
 
 /* ContextSensitive events. */
-document.observe('ContextSensitive:click', ImpMessage.contextOnClick.bindAsEventListener(ImpMessage));
+document.addEventListener('ContextSensitive:click', ImpMessage.contextOnClick.bind(ImpMessage));
 
 /* ImpCore handlers. */
-document.observe('ImpCore:updateAddressHeader', ImpMessage.updateAddressHeader.bindAsEventListener(ImpMessage));
+document.addEventListener('ImpCore:updateAddressHeader', ImpMessage.updateAddressHeader.bind(ImpMessage));
 
 /* Define reloadMessage() method for this page. */
 ImpCore.reloadMessage = function(params) {
diff --git a/js/passphrase.js b/js/passphrase.js
index e6604bdf7..5c7ce5c70 100644
--- a/js/passphrase.js
+++ b/js/passphrase.js
@@ -10,7 +10,7 @@ var ImpPassphraseDialog = {
 
     display: function(data)
     {
-        HordeDialog.display(Object.extend(data, {
+        HordeDialog.display(Object.assign(data, {
             form_id: 'imp_passphrase',
             password: true
         }));
@@ -18,11 +18,11 @@ var ImpPassphraseDialog = {
 
     onClick: function(e)
     {
-        switch (e.element().identify()) {
+        switch (e.target.id || (e.target.closest('[id]') || {}).id) {
         case 'imp_passphrase':
             HordeCore.doAction(
                 'checkPassphrase',
-                e.findElement('FORM').serialize(true),
+                Object.fromEntries(new FormData(e.target.closest('FORM'))),
                 { callback: this.callback.bind(this) }
             );
             break;
@@ -39,4 +39,4 @@ var ImpPassphraseDialog = {
 
 };
 
-document.observe('HordeDialog:onClick', ImpPassphraseDialog.onClick.bindAsEventListener(ImpPassphraseDialog));
+document.addEventListener('HordeDialog:onClick', ImpPassphraseDialog.onClick.bind(ImpPassphraseDialog));
diff --git a/js/prefs/acl.js b/js/prefs/acl.js
index 36cc77e15..862c24793 100644
--- a/js/prefs/acl.js
+++ b/js/prefs/acl.js
@@ -6,21 +6,29 @@
  * @license    GPL-2 (http://www.horde.org/licenses/gpl)
  */
 
-document.observe('dom:loaded', function() {
-    $('aclmbox').observe('change', function(e) {
-        $($('prefs').getInputs('checkbox')).flatten().invoke('disable');
-        $('change_acl_mbox').setValue(1);
-        $('prefs').submit();
+document.addEventListener('DOMContentLoaded', function() {
+    document.getElementById('aclmbox').addEventListener('change', function() {
+        document.getElementById('prefs').querySelectorAll('input[type="checkbox"]').forEach(function(i) {
+            i.disabled = true;
+        });
+        document.getElementById('change_acl_mbox').value = 1;
+        document.getElementById('prefs').submit();
     });
 
     /* Disable selection of container elements. */
-    $('aclmbox').select('OPTION[value=""]').invoke('writeAttribute', 'disabled', true);
+    document.getElementById('aclmbox').querySelectorAll('option[value=""]').forEach(function(o) {
+        o.disabled = true;
+    });
 
-    $$('TABLE.prefsAclTable')[0].on('change', 'SELECT.aclTemplate', function(e, elt) {
-        var acl = $F(elt);
+    document.querySelector('table.prefsAclTable').addEventListener('change', function(e) {
+        var elt = e.target;
+        if (!elt.matches('select.aclTemplate')) {
+            return;
+        }
 
-        elt.up('TR').select('INPUT[type=checkbox]').each(function(i) {
-            i.setValue(acl.include(i.value));
+        var acl = elt.value;
+        elt.closest('tr').querySelectorAll('input[type=checkbox]').forEach(function(i) {
+            i.checked = acl.includes(i.value);
         });
 
         elt.selectedIndex = 0;
diff --git a/js/prefs/flag.js b/js/prefs/flag.js
index 311f2bd34..0d6a947be 100644
--- a/js/prefs/flag.js
+++ b/js/prefs/flag.js
@@ -20,32 +20,32 @@ var ImpFlagPrefs = {
 
     _sendData: function(a, d)
     {
-        $('flag_action').setValue(a);
-        $('flag_data').setValue(d);
-        $('prefs').submit();
+        document.getElementById('flag_action').value = a;
+        document.getElementById('flag_data').value = d;
+        document.getElementById('prefs').submit();
     },
 
     changeHandler: function(e, elt)
     {
-        if (elt.identify().startsWith('bg_')) {
-            elt.setStyle({ background: elt.getValue() });
+        if (elt.id.startsWith('bg_')) {
+            elt.style.background = elt.value;
         }
     },
 
     clickHandler: function(e)
     {
         var cnames, elt2,
-            elt = e.element();
+            elt = e.detail.element();
 
-        if (elt.readAttribute('id') == 'new_button') {
+        if (elt.id == 'new_button') {
             this.addFlag();
         } else {
-            cnames = $w(elt.className);
+            cnames = elt.className.split(/\s+/);
 
             if (cnames.indexOf('flagcolorpicker') !== -1) {
-                elt2 = elt.previous('INPUT');
+                elt2 = elt.previousElementSibling;
                 new ColorPicker({
-                    color: $F(elt2),
+                    color: elt2.value,
                     draggable: true,
                     offsetParent: elt,
                     resizable: true,
@@ -54,21 +54,21 @@ var ImpFlagPrefs = {
                         [ elt2, 'background' ]
                     ]
                 });
-                e.memo.stop();
+                e.detail.stop();
             } else if (cnames.indexOf('flagdelete') !== -1) {
                 if (window.confirm(this.confirm_delete)) {
-                    this._sendData('delete', elt.previous('INPUT').readAttribute('id'));
+                    this._sendData('delete', elt.previousElementSibling.id);
                 }
-                e.memo.stop();
+                e.detail.stop();
             }
         }
     },
 
     resetHandler: function()
     {
-        $('prefs').getInputs('text').each(function(i) {
-            if (i.readAttribute('id').startsWith('color_')) {
-                i.setStyle({ backgroundColor: $F(i) });
+        document.getElementById('prefs').querySelectorAll('input[type="text"]').forEach(function(i) {
+            if (i.id.startsWith('color_')) {
+                i.style.backgroundColor = i.value;
             }
         });
     },
@@ -76,13 +76,17 @@ var ImpFlagPrefs = {
     onDomLoad: function()
     {
         HordeCore.initHandler('click');
-        $('prefs').observe('reset', function() {
-            this.resetHandler.delay(0.1);
+        document.getElementById('prefs').addEventListener('reset', function() {
+            setTimeout(this.resetHandler.bind(this), 100);
         }.bind(this));
     }
 
 };
 
-document.observe('dom:loaded', ImpFlagPrefs.onDomLoad.bind(ImpFlagPrefs));
-document.observe('HordeCore:click', ImpFlagPrefs.clickHandler.bindAsEventListener(ImpFlagPrefs));
-document.on('change', 'INPUT', ImpFlagPrefs.changeHandler.bind(ImpFlagPrefs));
+document.addEventListener('DOMContentLoaded', ImpFlagPrefs.onDomLoad.bind(ImpFlagPrefs));
+document.addEventListener('HordeCore:click', ImpFlagPrefs.clickHandler.bind(ImpFlagPrefs));
+document.addEventListener('change', function(e) {
+    if (e.target.matches('INPUT')) {
+        ImpFlagPrefs.changeHandler(e, e.target);
+    }
+});
diff --git a/js/prefs/pgp.js b/js/prefs/pgp.js
index 409557a00..175358ff7 100644
--- a/js/prefs/pgp.js
+++ b/js/prefs/pgp.js
@@ -10,22 +10,25 @@ var ImpPgp = {
 
     replaceDate: function(d)
     {
-        $('generate_expire_date').setValue(d.getTime()).next('SPAN').update(this.months[d.getMonth()] + ' ' + d.getDate() + ', ' + (d.getFullYear()));
+        var elt = document.getElementById('generate_expire_date');
+        elt.value = d.getTime();
+        elt.nextElementSibling.textContent = this.months[d.getMonth()] + ' ' + d.getDate() + ', ' + d.getFullYear();
     },
 
     clickHandler: function(e)
     {
-        var elt = e.element();
+        var elt = e.detail.element();
 
-        switch (elt.readAttribute('id')) {
+        switch (elt.id) {
         case 'generate_expire':
-            elt.next().toggle();
+            var sib = elt.nextElementSibling;
+            sib.hidden = !sib.hidden;
             break;
 
         default:
-            if (elt.hasClassName('calendarImg')) {
-                Horde_Calendar.open(elt.identify(), new Date(Number($('generate_expire_date').getValue())));
-                e.memo.stop();
+            if (elt.classList.contains('calendarImg')) {
+                Horde_Calendar.open(elt.id, new Date(Number(document.getElementById('generate_expire_date').value)));
+                e.detail.stop();
             }
             break;
         }
@@ -33,7 +36,7 @@ var ImpPgp = {
 
     calendarSelectHandler: function(e)
     {
-        this.replaceDate(e.memo);
+        this.replaceDate(e.detail);
     },
 
     onDomLoad: function()
@@ -47,6 +50,6 @@ var ImpPgp = {
 
 };
 
-document.observe('dom:loaded', ImpPgp.onDomLoad.bind(ImpPgp));
-document.observe('HordeCore:click', ImpPgp.clickHandler.bindAsEventListener(ImpPgp));
-document.observe('Horde_Calendar:select', ImpPgp.calendarSelectHandler.bindAsEventListener(ImpPgp));
+document.addEventListener('DOMContentLoaded', ImpPgp.onDomLoad.bind(ImpPgp));
+document.addEventListener('HordeCore:click', ImpPgp.clickHandler.bind(ImpPgp));
+document.addEventListener('Horde_Calendar:select', ImpPgp.calendarSelectHandler.bind(ImpPgp));
diff --git a/js/prefs/remote.js b/js/prefs/remote.js
index 8f363d6e4..c11c6530b 100644
--- a/js/prefs/remote.js
+++ b/js/prefs/remote.js
@@ -13,91 +13,95 @@ var ImpRemotePrefs = {
 
     _sendData: function(a, d, c)
     {
-        $('remote_action').setValue(a);
-        $('remote_data').setValue(d);
+        document.getElementById('remote_action').value = a;
+        document.getElementById('remote_data').value = d;
         if (c) {
-            $('prefs').getInputs('hidden', 'actionID').first().clear();
+            document.querySelector('#prefs input[type="hidden"][name="actionID"]').value = '';
         }
-        $('prefs').submit();
+        document.getElementById('prefs').submit();
     },
 
     _autoconfigCallback: function(r)
     {
         if (r.success) {
-            $('remote_type').setValue(r.mconfig.imap ? 'imap' : 'pop3');
-            $('remote_server').setValue(r.mconfig.host);
-            $('remote_user').setValue(r.mconfig.username);
-            $('remote_port').setValue(r.mconfig.port);
-            $('remote_secure_autoconfig').setValue(r.mconfig.tls);
-
-            if ($F('remote_label').blank()) {
-                $('remote_label').setValue(r.mconfig.label);
+            document.getElementById('remote_type').value = r.mconfig.imap ? 'imap' : 'pop3';
+            document.getElementById('remote_server').value = r.mconfig.host;
+            document.getElementById('remote_user').value = r.mconfig.username;
+            document.getElementById('remote_port').value = r.mconfig.port;
+            document.getElementById('remote_secure_autoconfig').value = r.mconfig.tls;
+
+            if (!document.getElementById('remote_label').value.trim()) {
+                document.getElementById('remote_label').value = r.mconfig.label;
             }
 
-            $('remote_password').remove();
-            $('autoconfig_button').hide();
-            $('add_button').show();
+            document.getElementById('remote_password').remove();
+            document.getElementById('autoconfig_button').hidden = true;
+            document.getElementById('add_button').hidden = false;
         } else {
-            $('autoconfig_button').setValue(this.next);
+            document.getElementById('autoconfig_button').value = this.next;
         }
 
-        $('prefs').enable();
+        Array.from(document.getElementById('prefs').elements).forEach(function(el) {
+            el.disabled = false;
+        });
     },
 
     clickHandler: function(e)
     {
-        if (e.isRightClick()) {
+        if (e.button === 2) {
             return;
         }
 
-        var elt = e.element();
+        var elt = e.target;
 
-        while (Object.isElement(elt)) {
-            if (elt.hasClassName('remotedelete')) {
+        while (elt instanceof Element) {
+            if (elt.classList.contains('remotedelete')) {
                 if (window.confirm(this.confirm_delete)) {
-                    this._sendData('delete', elt.readAttribute('data-id'));
+                    this._sendData('delete', elt.dataset.id);
                 }
-                e.stop();
+                e.preventDefault();
                 return;
             }
 
-            switch (elt.readAttribute('id')) {
+            switch (elt.id) {
             case 'add_button':
                 this._sendData('add', '');
                 break;
 
             case 'autoconfig_button':
-                if ($F('remote_email').blank()) {
+                if (!document.getElementById('remote_email').value.trim()) {
                     window.alert(this.empty_email);
-                } else if ($F('remote_password').empty()) {
+                } else if (!document.getElementById('remote_password').value) {
                     window.alert(this.empty_password);
                 } else {
                     HordeCore.doAction(
                         'autoconfigAccount',
                         {
-                            email: $F('remote_email'),
-                            // Base64 encode just to keep password data from
-                            // being plaintext. A trivial obfuscation, but
-                            // will prevent passwords from leaking in the
-                            // event of some sort of data dump.
-                            password: Base64.encode($F('remote_password')),
+                            email: document.getElementById('remote_email').value,
+                            password: Base64.encode(document.getElementById('remote_password').value),
                             password_base64: true,
-                            secure: ~~($F('remote_secure') == 'yes')
+                            secure: ~~(document.getElementById('remote_secure').value == 'yes')
                         },
                         {
                             callback: this._autoconfigCallback.bind(this)
                         }
                     );
-                    elt.setValue(this.wait);
-                    $('prefs').disable();
+                    elt.value = this.wait;
+                    Array.from(document.getElementById('prefs').elements).forEach(function(el) {
+                        el.disabled = true;
+                    });
                 }
-                e.stop();
+                e.preventDefault();
                 break;
 
             case 'advanced_show':
-                $('prefs').select('.imp-remote-autoconfig').invoke('hide');
-                $('remote_secure_autoconfig').remove();
-                $('prefs').select('.imp-remote-advanced').invoke('show');
+                document.querySelectorAll('#prefs .imp-remote-autoconfig').forEach(function(el) {
+                    el.hidden = true;
+                });
+                document.getElementById('remote_secure_autoconfig').remove();
+                document.querySelectorAll('#prefs .imp-remote-advanced').forEach(function(el) {
+                    el.hidden = false;
+                });
                 break;
 
             case 'cancel_button':
@@ -109,10 +113,10 @@ var ImpRemotePrefs = {
                 break;
             }
 
-            elt = elt.up();
+            elt = elt.parentElement;
         }
     }
 
 };
 
-document.observe('click', ImpRemotePrefs.clickHandler.bindAsEventListener(ImpRemotePrefs));
+document.addEventListener('click', ImpRemotePrefs.clickHandler.bind(ImpRemotePrefs));
diff --git a/js/prefs/signaturehtml.js b/js/prefs/signaturehtml.js
index 6d0e80139..c521a2089 100644
--- a/js/prefs/signaturehtml.js
+++ b/js/prefs/signaturehtml.js
@@ -12,12 +12,12 @@ var ImpHtmlSignaturePrefs = {
 
     changeIdentity: function(e)
     {
-        switch (e.memo.pref) {
+        switch (e.detail.pref) {
         case 'signature_html_select':
             if (this.editor) {
-                this.editor.setData(this.sigs[e.memo.i]);
+                this.editor.setData(this.sigs[e.detail.i]);
             } else {
-                this.changeIdentity.bind(this, e).delay(0.1);
+                setTimeout(this.changeIdentity.bind(this, e), 100);
             }
             break;
         }
@@ -72,5 +72,5 @@ var ImpHtmlSignaturePrefs = {
 
 };
 
-document.observe('dom:loaded', ImpHtmlSignaturePrefs.onDomLoad.bind(ImpHtmlSignaturePrefs));
-document.observe('HordeIdentitySelect:change', ImpHtmlSignaturePrefs.changeIdentity.bindAsEventListener(ImpHtmlSignaturePrefs));
+document.addEventListener('DOMContentLoaded', ImpHtmlSignaturePrefs.onDomLoad.bind(ImpHtmlSignaturePrefs));
+document.addEventListener('HordeIdentitySelect:change', ImpHtmlSignaturePrefs.changeIdentity.bind(ImpHtmlSignaturePrefs));
diff --git a/js/syntaxhighlighter.js b/js/syntaxhighlighter.js
index c7d1e3915..6afa5ffb3 100644
--- a/js/syntaxhighlighter.js
+++ b/js/syntaxhighlighter.js
@@ -1 +1,4 @@
-$('messageBody') && $('messageBody').observe('IMP_Preview:loadedFromCache', function() { window.SyntaxHighlighter.highlight(); });
+var mb = document.getElementById('messageBody');
+if (mb) {
+    mb.addEventListener('IMP_Preview:loadedFromCache', function() { window.SyntaxHighlighter.highlight(); });
+}
diff --git a/js/viewport_utils.js b/js/viewport_utils.js
index 4917971ee..b3786967d 100644
--- a/js/viewport_utils.js
+++ b/js/viewport_utils.js
@@ -6,20 +6,20 @@
  * @license    GPL-2 (http://www.horde.org/licenses/gpl)
  */
 
-Object.extend(Array.prototype, {
+Object.assign(Array.prototype, {
 
     // Need our own diff() function because prototypejs's without() function
     // does not handle array input.
     diff: function(values)
     {
-        return this.select(function(value) {
-            return !values.include(value);
+        return this.filter(function(value) {
+            return values.indexOf(value) === -1;
         });
     },
 
     numericSort: function()
     {
-        return this.collect(Number).sort(function(a, b) {
+        return this.map(Number).sort(function(a, b) {
             return (a > b) ? 1 : ((a < b) ? -1 : 0);
         });
     },
@@ -30,12 +30,12 @@ Object.extend(Array.prototype, {
     {
         opts = opts || {};
 
-        var u = (opts.raw ? this.clone() : this.numericSort()),
+        var u = (opts.raw ? this.slice() : this.numericSort()),
             first = u.shift(),
             last = first,
             out = [];
 
-        u.each(function(k) {
+        u.forEach(function(k) {
             if (!opts.raw && (last + 1 == k)) {
                 last = k;
             } else {
@@ -50,18 +50,21 @@ Object.extend(Array.prototype, {
 
 });
 
-Object.extend(String.prototype, {
+Object.assign(String.prototype, {
 
     parseViewportUidString: function()
     {
         var out = [];
 
-        this.strip().split(',').each(function(e) {
+        this.trim().split(',').forEach(function(e) {
             var r = e.split(':');
-            if (r.size() == 1) {
+            if (r.length == 1) {
                 out.push(Number(e));
             } else {
-                out = out.concat($A($R(Number(r[0]), Number(r[1]))));
+                var start = Number(r[0]), end = Number(r[1]);
+                for (var i = start; i <= end; i++) {
+                    out.push(i);
+                }
             }
         });
 
diff --git a/lib/Compose.php b/lib/Compose.php
index 2b05468a3..153295303 100644
--- a/lib/Compose.php
+++ b/lib/Compose.php
@@ -3503,7 +3503,7 @@ protected function _addAttachment($atc_file, $bytes, $filename, $type)
     /**
      * Store draft compose data if session expires.
      *
-     * @param Horde_Variables $vars  Object with the form data.
+     * @param Horde_Variables|Variables $vars  Object with the form data.
      */
     public function sessionExpireDraft(Variables|Horde_Variables $vars)
     {
diff --git a/lib/Contents/View.php b/lib/Contents/View.php
index 65d05a837..0718d6896 100644
--- a/lib/Contents/View.php
+++ b/lib/Contents/View.php
@@ -338,7 +338,7 @@ public function printAttach($id)
     /**
      * Check for a download token.
      *
-     * @param Horde_Variables $vars  Form variables.
+     * @param Horde_Variables|Variables $vars  Form variables.
      *
      * @throws Horde_Exception  Exception on incorrect token.
      */
diff --git a/lib/Dynamic/Compose.php b/lib/Dynamic/Compose.php
index 98ecdb847..d96c9d16e 100644
--- a/lib/Dynamic/Compose.php
+++ b/lib/Dynamic/Compose.php
@@ -267,7 +267,7 @@ public static function url(array $opts = [])
     /**
      * Create the IMP_Contents objects needed to create a message.
      *
-     * @param Horde_Variables $vars  The variables object.
+     * @param Horde_Variables|Variables $vars  The variables object.
      *
      * @return IMP_Contents  The IMP_Contents object.
      * @throws IMP_Exception