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more work on mock dom loading, per #113
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@getify
getify committed Mar 26, 2017
1 parent 783002f commit 2ae6907
Showing 1 changed file with 198 additions and 28 deletions.
226 changes: 198 additions & 28 deletions mock-dom-resource-loading.js
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Expand Up @@ -13,15 +13,33 @@
// **************************************

function createMockDOM(opts) {
opts = opts || {};
opts = opts ? JSON.parse( JSON.stringify( opts ) ) : {};
if (!("relList" in opts)) opts.relList = true;
if (!("scriptAsync" in opts)) opts.scriptAsync = true;
if (!("linkPreload" in opts)) opts.linkPreload = true;
if (!("baseURI" in opts)) opts.baseURI = "";
if (!("log" in opts)) opts.log = function log(status) { console.log( JSON.stringify( status ) ); }
if (!("error" in opts)) opts.error = function error(err) { throw err; };
if (!("resources" in opts)) opts.resources = [];

// setup Element prototype
Element.prototype.getElementsByTagName = getElementsByTagName;
Element.prototype.appendChild = appendChild;
Element.prototype.removeChild = removeChild;
Element.prototype.setAttribute = setAttribute;
Element.prototype.getAttribute = getAttribute;
Element.prototype.addEventListener = addEventListener;
Element.prototype.removeEventListener = removeEventListener;
Element.prototype.dispatchEvent = dispatchEvent;

var loadQueue = [];
var silent = true;

var documentElement = createElement( "document" );
documentElement.head = createElement( "head" );
documentElement.body = createElement( "body" );
documentElement.appendChild( documentElement.head );
documentElement.appendChild( documentElement.body );
documentElement.baseURI = opts.baseURI;
documentElement.createElement = createElement;

Expand All @@ -33,14 +51,13 @@
mockDOM.document = documentElement;
mockDOM.performance = performanceAPI;

// setup Element prototype
Element.prototype.getElementsByTagName = getElementsByTagName;
Element.prototype.appendChild = appendChild;
Element.prototype.removeChild = removeChild;
Element.prototype.setAttribute = setAttribute;
Element.prototype.getAttribute = getAttribute;
Element.prototype.addEventListener = addEventListener;
Element.prototype.removeEventListener = removeEventListener;
silent = false;

// notify: internal IDs for built-ins
opts.log( {window: mockDOM._internal_id} );
opts.log( {document: documentElement._internal_id} );
opts.log( {head: documentElement.head._internal_id} );
opts.log( {body: documentElement.body._internal_id} );

return mockDOM;

Expand All @@ -54,9 +71,17 @@
var element = new Element();
element.tagName = tagName.toUpperCase();

!silent && opts.log( {createElement: tagName, internal_id: element._internal_id} );

if (tagName == "script") {
element.async = !!opts.scriptAsync;
}
if (tagName == "link") {
element.href = "";
}
if (/^(?:script|img)$/.test( tagName )) {
element.src = "";
}

return element;
}
Expand All @@ -73,34 +98,64 @@
}

// ************
this.tagNameTagNameNodeLists = {};
this._internal_id = Math.floor( Math.random() * 1E6 );
this._tagNameNodeLists = {};
this._eventHandlers = {};
}

// Element#getElementsByTagName(..)
function getElementsByTagName(tagName) {
this.tagNameTagNameNodeLists[tagName] = this.tagNameTagNameNodeLists[tagName] || [];
return this.tagNameTagNameNodeLists[tagName];
this._tagNameNodeLists[tagName] = this._tagNameNodeLists[tagName] || [];
return this._tagNameNodeLists[tagName];
}

// Element#appendChild(..)
function appendChild(childElement) {
!silent && opts.log( {appendChild: childElement._internal_id, internal_id: this._internal_id} );

this.childNodes.push( childElement );
childElement.parentNode = this;
updateTagNameNodeLists( childElement );

if (childElement.tagName == "link" && childElement.rel == "preload") {
// TODO: simulate resource preloading
if (childElement.tagName.toLowerCase() == "link" && childElement.rel == "preload") {
var resource = findMatchingOptResource( childElement.href );

if (resource) {
fakePreload( resource, childElement );
}
else {
opts.error( new Error( "appendChild: Preload resource not found (" + childElement.href + "; " + childElement._internal_id + ")" ) );
}
}
else if (/^(?:script|link|img)$/i.test( childElement.tagName )) {
var url = (/^(?:script|img)$/i.test( childElement.tagName )) ?
childElement.src :
childElement.href;
var resource = findMatchingOptResource( url );

if (resource) {
// track load-order queue (for ordered-async on scripts)?
if (opts.scriptAsync && childElement.tagName.toLowerCase() == "script" && childElement.async === false) {
loadQueue.push( {url: url, element: childElement} );
}

fakeLoad( resource, childElement );
}
else {
opts.error( new Error( "appendChild: Load resource not found (" + url + "; " + childElement._internal_id + ")" ) );
}
}
else if (/^(?:script|link|img)$/.test( childElement.tagName )) {
// TODO: simulate resource loading
else {
!silent && opts.error( new Error( "appendChild: Unrecognized tag (" + childElement.tagName + "; " + childElement._internal_id + ")" ) );
}

return childElement;
}

// Element#removeChild(..)
function removeChild(childElement) {
opts.log( {removeChild: childElement._internal_id, internal_id: this._internal_id} );

var idx = this.childNodes.indexOf( childElement );
if (idx != -1) {
this.childNodes.splice( idx, 1 );
Expand All @@ -113,6 +168,8 @@

// Element#setAttribute(..)
function setAttribute(attrName,attrValue) {
opts.log( {setAttribute: attrName + " | " + attrValue, internal_id: this._internal_id} );

this[attrName] = attrValue;
}

Expand All @@ -123,21 +180,36 @@

// Element#addEventListener(..)
function addEventListener(evtName,handler) {
this._evtHandlers[evtName] = this._evtHandlers[evtName] || [];
this._evtHandlers[evtName].push( handler );
opts.log( {addEventListener: evtName, internal_id: this._internal_id} );

this._eventHandlers[evtName] = this._eventHandlers[evtName] || [];
this._eventHandlers[evtName].push( handler );
}

// Element#removeEventListener(..)
function removeEventListener(evtName,handler) {
if (this._evtHandlers[evtName]) {
var idx = this._evtHandlers[evtName].indexOf( handler );
this._evtHandlers[evtName].splice( idx, 1 );
opts.log( {removeEventListener: evtName, internal_id: this._internal_id} );

if (this._eventHandlers[evtName]) {
var idx = this._eventHandlers[evtName].indexOf( handler );
this._eventHandlers[evtName].splice( idx, 1 );
}
}

// Element#dispatchEvent(..)
function dispatchEvent(evt) {
opts.log( {dispatchEvent: evt.type, internal_id: this._internal_id} );

if (this._eventHandlers[evt.type]) {
for (var i = 0; i < this._eventHandlers[evt.type].length; i++) {
try { this._eventHandlers[evt.type][i].call( this, evt ); } catch (err) {}
}
}
}

// Element#relList.supports(..)
function supports(feature) {
if (feature == "preload" && opts.linkPreload && this._parent.tagName == "link") {
function supports(rel) {
if (rel == "preload" && opts.linkPreload && this._parent.tagName.toLowerCase() == "link") {
return true;
}
return false;
Expand All @@ -156,9 +228,9 @@

// recursively walk up the element tree
while (el != null) {
el.tagNameTagNameNodeLists[element.tagName] = el.tagNameTagNameNodeLists[element.tagName] || [];
if (!~el.tagNameTagNameNodeLists[element.tagName].indexOf( element )) {
el.tagNameTagNameNodeLists[element.tagName].push( element );
el._tagNameNodeLists[element.tagName] = el._tagNameNodeLists[element.tagName] || [];
if (!~el._tagNameNodeLists[element.tagName].indexOf( element )) {
el._tagNameNodeLists[element.tagName].push( element );
}
el = el.parentNode;
}
Expand All @@ -170,11 +242,109 @@
// recursively walk up the element tree
while (el != null) {
var idx;
if (el.tagNameTagNameNodeLists[element.tagName] && (idx = el.tagNameTagNameNodeLists[element.tagName].indexOf( element )) != -1) {
el.tagNameTagNameNodeLists[element.tagName].splice( idx, 1 );
if (el._tagNameNodeLists[element.tagName] && (idx = el._tagNameNodeLists[element.tagName].indexOf( element )) != -1) {
el._tagNameNodeLists[element.tagName].splice( idx, 1 );
}
el = el.parentNode;
}
}

function findMatchingOptResource(url) {
for (var i = 0; i < opts.resources.length; i++) {
if (opts.resources[i].url == url) {
return opts.resources[i];
}
}
}

function fakePreload(resource,element) {
setTimeout( function preload(){
if (resource.preload === true) {
var evt = createEvent( "load", element );
}
else {
var evt = createEvent( "error", element );
}

element.dispatchEvent( evt );
}, resource.preloadDelay || 0 );
}

function fakeLoad(resource,element) {
if (resource.load === true) {
var evt = createEvent( "load", element );
}
else {
var evt = createEvent( "error", element );
}

setTimeout( function load(){
// simulating ordered-async for <script> elements?
if (opts.scriptAsync && element.tagName.toLowerCase() == "script" && element.async === false) {
updateLoadQueue( resource.url, element, evt );
}
else {
element.dispatchEvent( evt );
}
}, resource.loadDelay || 0 );
}

function createEvent(type,target) {
return {
type: type,
name: type,
target: target,
currentTarget: target,
bubbles: false,
cancelable: false,
composed: false,
scoped: false,
defaultPrevented: false,
timestamp: Date.now(),
isTrusted: true,
eventPhase: 2, // Event.AT_TARGET
preventDefault: function(){ this.defaultPrevented = true; },
stopPropagation: function(){},
stopImmediatePropagation: function(){},
};
}

// ensures load event order (queue) for ordered-async
function updateLoadQueue(url,element,evt) {
var found = false;
var dispatchReady = true;
var idx = 0;

while (loadQueue.length > 0 && idx < loadQueue.length) {
// update queue item?
if (loadQueue[idx].url == url && loadQueue[idx].element == element) {
opts.log( {updateLoadQueue: url, internal_id: element._internal_id} );
loadQueue[idx].evt = evt;
found = true;
}

if (dispatchReady) {
var entry = loadQueue[0];

if (entry.evt) {
entry.element.dispatchEvent( entry.evt );
loadQueue.shift();
// NOTE: since we're shifting off index 0, no need
// to increment `idx`
}
else {
dispatchReady = false;
idx++;
}
}
else {
idx++;
}
}

if (!found) {
opts.error( new Error( "updateLoadQueue: Entry not found (" + url + "; " + element._internal_id + ")" ) );
}
}
}
});

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