mousetrap.js

/**
 * Copyright 2012 Craig Campbell
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Mousetrap is a simple keyboard shortcut library for Javascript with
 * no external dependencies
 *
 * @preserve @version 1.1
 * @url craig.is/killing/mice
 */
window.Mousetrap = (function() {

    /**
     * mapping of special keycodes to their corresponding keys
     *
     * everything in this dictionary cannot use keypress events
     * so it has to be here to map to the correct keycodes for
     * keyup/keydown events
     *
     * @type {Object}
     */
    var _MAP = {
            8: 'backspace',
            9: 'tab',
            13: 'enter',
            16: 'shift',
            17: 'ctrl',
            18: 'alt',
            20: 'capslock',
            27: 'esc',
            32: 'space',
            33: 'pageup',
            34: 'pagedown',
            35: 'end',
            36: 'home',
            37: 'left',
            38: 'up',
            39: 'right',
            40: 'down',
            45: 'ins',
            46: 'del',
            91: 'meta',
            93: 'meta',
            224: 'meta'
        },

        /**
         * mapping for special characters so they can support
         *
         * this dictionary is only used incase you want to bind a
         * keyup or keydown event to one of these keys
         *
         * @type {Object}
         */
        _KEYCODE_MAP = {
            106: '*',
            107: '+',
            109: '-',
            110: '.',
            111 : '/',
            186: ';',
            187: '=',
            188: ',',
            189: '-',
            190: '.',
            191: '/',
            192: '`',
            219: '[',
            220: '\\',
            221: ']',
            222: '\''
        },

        /**
         * this is a mapping of keys that require shift on a US keypad
         * back to the non shift equivelents
         *
         * this is so you can use keyup events with these keys
         *
         * note that this will only work on US keyboards
         *
         * @type {Object}
         */
        _SHIFT_MAP = {
            '~': '`',
            '!': '1',
            '@': '2',
            '#': '3',
            '$': '4',
            '%': '5',
            '^': '6',
            '&': '7',
            '*': '8',
            '(': '9',
            ')': '0',
            '_': '-',
            '+': '=',
            ':': ';',
            '\"': '\'',
            '<': ',',
            '>': '.',
            '?': '/',
            '|': '\\'
        },

        /**
         * this is a list of special strings you can use to map
         * to modifier keys when you specify your keyboard shortcuts
         *
         * @type {Object}
         */
        _SPECIAL_ALIASES = {
            'option': 'alt',
            'command': 'meta',
            'return': 'enter',
            'escape': 'esc'
        },

        /**
         * variable to store the flipped version of _MAP from above
         * needed to check if we should use keypress or not when no action
         * is specified
         *
         * @type {Object|undefined}
         */
        _REVERSE_MAP,

        /**
         * a list of all the callbacks setup via Mousetrap.bind()
         *
         * @type {Object}
         */
        _callbacks = {},

        /**
         * direct map of string combinations to callbacks used for trigger()
         *
         * @type {Object}
         */
        _direct_map = {},

        /**
         * keeps track of what level each sequence is at since multiple
         * sequences can start out with the same sequence
         *
         * @type {Object}
         */
        _sequence_levels = {},

        /**
         * variable to store the setTimeout call
         *
         * @type {null|number}
         */
        _reset_timer,

        /**
         * temporary state where we will ignore the next keyup
         *
         * @type {boolean|string}
         */
        _ignore_next_keyup = false,

        /**
         * are we currently inside of a sequence?
         * type of action ("keyup" or "keydown" or "keypress") or false
         *
         * @type {boolean|string}
         */
        _inside_sequence = false;

    /**
     * loop through the f keys, f1 to f19 and add them to the map
     * programatically
     */
    for (var i = 1; i < 20; ++i) {
        _MAP[111 + i] = 'f' + i;
    }

    /**
     * loop through to map numbers on the numeric keypad
     */
    for (i = 96; i < 106; ++i) {
        _MAP[i] = i - 96;
    }

    /**
     * cross browser add event method
     *
     * @param {Element|HTMLDocument} object
     * @param {string} type
     * @param {Function} callback
     * @returns void
     */
    function _addEvent(object, type, callback) {
        if (object.addEventListener) {
            return object.addEventListener(type, callback, false);
        }

        object.attachEvent('on' + type, callback);
    }

    /**
     * takes the event and returns the keycode
     *
     * @param {Event} e
     * @return {string}
     */
    function _characterFromEvent(e) {

        // for keypress events we should return the character as is
        if (e.type == 'keypress') {
            return String.fromCharCode(e.which);
        }

        // for non keypress events the special maps are needed
        if (_MAP[e.which]) {
            return _MAP[e.which];
        }

        if (_KEYCODE_MAP[e.which]) {
            return _KEYCODE_MAP[e.which];
        }

        // if it is not in the special map
        return String.fromCharCode(e.which).toLowerCase();
    }

    /**
     * should we stop this event before firing off callbacks
     *
     * @param {Event} e
     * @return {boolean}
     */
    function _stop(e) {
        var element = e.target || e.srcElement,
            tag_name = element.tagName;

        // if the element has the class "mousetrap" then no need to stop
        if ((' ' + element.className + ' ').indexOf(' mousetrap ') > -1) {
            return false;
        }

        // stop for input, select, and textarea
        return tag_name == 'INPUT' || tag_name == 'SELECT' || tag_name == 'TEXTAREA'/* || element.getAttribute('contenteditable')*/;
    }

    /**
     * checks if two arrays are equal
     *
     * @param {Array} modifiers1
     * @param {Array} modifiers2
     * @returns {boolean}
     */
    function _modifiersMatch(modifiers1, modifiers2) {
        return modifiers1.sort().join(',') === modifiers2.sort().join(',');
    }

    /**
     * resets all sequence counters except for the ones passed in
     *
     * @param {Object} do_not_reset
     * @returns void
     */
    function _resetSequences(do_not_reset) {
        do_not_reset = do_not_reset || {};

        var active_sequences = false;

        for (var key in _sequence_levels) {
            if (!do_not_reset[key]) {
                _sequence_levels[key] = 0;
                continue;
            }
            active_sequences = true;
        }

        if (!active_sequences) {
            _inside_sequence = false;
        }
    }

    /**
     * finds all callbacks that match based on the keycode, modifiers,
     * and action
     *
     * @param {string} character
     * @param {Array} modifiers
     * @param {string} action
     * @param {boolean=} remove - should we remove any matches
     * @param {string=} combination
     * @returns {Array}
     */
    function _getMatches(character, modifiers, action, remove, combination) {
        var i,
            callback,
            matches = [];

        // if there are no events related to this keycode
        if (!_callbacks[character]) {
            return [];
        }

        // if a modifier key is coming up on its own we should allow it
        if (action == 'keyup' && _isModifier(character)) {
            modifiers = [character];
        }

        // loop through all callbacks for the key that was pressed
        // and see if any of them match
        for (i = 0; i < _callbacks[character].length; ++i) {
            callback = _callbacks[character][i];

            // if this is a sequence but it is not at the right level
            // then move onto the next match
            if (callback['seq'] && _sequence_levels[callback['seq']] != callback['level']) {
                continue;
            }

            // if the action we are looking for doesn't match the action we got
            // then we should keep going
            if (action != callback.action) {
                continue;
            }

            // if this is a keypress event that means that we need to only
            // look at the character, otherwise check the modifiers as
            // well
            if (action === 'keypress' || _modifiersMatch(modifiers, callback.modifiers)) {

                // remove is used so if you change your mind and call bind a
                // second time with a new function the first one is overwritten
                if (remove && callback['combo'] == combination) {
                    _callbacks[character].splice(i, 1);
                }

                matches.push(callback);
            }
        }

        return matches;
    }

    /**
     * takes a key event and figures out what the modifiers are
     *
     * @param {Event} e
     * @returns {Array}
     */
    function _eventModifiers(e) {
        var modifiers = [];

        if (e.shiftKey) {
            modifiers.push('shift');
        }

        if (e.altKey) {
            modifiers.push('alt');
        }

        if (e.ctrlKey) {
            modifiers.push('ctrl');
        }

        if (e.metaKey) {
            modifiers.push('meta');
        }

        return modifiers;
    }

    /**
     * actually calls the callback function
     *
     * if your callback function returns false this will use the jquery
     * convention - prevent default and stop propogation on the event
     *
     * @param {Function}
     * @param {Event}
     * @returns void
     */
    function _callback(callback, e) {
        if (callback(e) === false) {
            if (e.preventDefault) {
                e.preventDefault();
            }

            if (e.stopPropagation) {
                e.stopPropagation();
            }

            e.returnValue = false;
            e.cancelBubble = true;
        }
    }

    /**
     * fires a callback for a matching keycode
     *
     * @param {string} character
     * @param {Event} e
     * @returns void
     */
    function _fireCallback(character, e) {

        // if this event should not happen stop here
        if (_stop(e)) {
            return;
        }

        var callbacks = _getMatches(character, _eventModifiers(e), e.type),
            i,
            do_not_reset = {},
            processed_sequence_callback = false;

        // loop through matching callbacks for this key event
        for (i = 0; i < callbacks.length; ++i) {

            // fire for all sequence callbacks
            // this is because if for example you have multiple sequences
            // bound such as "g i" and "g t" they both need to fire the
            // callback for matching g cause otherwise you can only ever
            // match the first one
            if (callbacks[i]['seq']) {
                processed_sequence_callback = true;

                // keep a list of which sequences were matches for later
                do_not_reset[callbacks[i]['seq']] = 1;
                _callback(callbacks[i].callback, e);
                continue;
            }

            // if there were no sequence matches but we are still here
            // that means this is a regular match so we should fire then break
            if (!processed_sequence_callback && !_inside_sequence) {
                _callback(callbacks[i].callback, e);
            }
        }

        // if you are inside of a sequence and the key you are pressing
        // is not a modifier key then we should reset all sequences
        // that were not matched by this key event
        if (e.type == _inside_sequence && !_isModifier(character)) {
            _resetSequences(do_not_reset);
        }
    }

    /**
     * handles a keydown event
     *
     * @param {Event} e
     * @returns void
     */
    function _handleKey(e) {

        // add which for key events
        // @see http://stackoverflow.com/questions/4285627/javascript-keycode-vs-charcode-utter-confusion
        e.which = typeof e.which == "number" ? e.which : e.keyCode;

        var character = _characterFromEvent(e);

        // no character found then stop
        if (!character) {
            return;
        }

        if (e.type === 'keyup' && _ignore_next_keyup === character) {
            _ignore_next_keyup = false;
            return;
        }

        _fireCallback(character, e);
    }

    /**
     * determines if the keycode specified is a modifier key or not
     *
     * @param {string} key
     * @returns {boolean}
     */
    function _isModifier(key) {
        return key == 'shift' || key == 'ctrl' || key == 'alt' || key == 'meta';
    }

    /**
     * called to set a 1 second timeout on the specified sequence
     *
     * this is so after each key press in the sequence you have 1 second
     * to press the next key before you have to start over
     *
     * @returns void
     */
    function _resetSequence() {
        clearTimeout(_reset_timer);
        _reset_timer = setTimeout(_resetSequences, 1000);
    }

    /**
     * reverses the map lookup so that we can look for specific keys
     * to see what can and can't use keypress
     *
     * @return {Object}
     */
    function _getReverseMap() {
        if (!_REVERSE_MAP) {
            _REVERSE_MAP = {};
            for (var key in _MAP) {

                // pull out the numberic keypad from here cause keypress should
                // be able to detect the keys from the character
                if (key > 95 && key < 112) {
                    continue;
                }

                if (_MAP.hasOwnProperty(key)) {
                    _REVERSE_MAP[_MAP[key]] = key;
                }
            }
        }
        return _REVERSE_MAP;
    }

    /**
     * picks the best action based on the key combination
     *
     * @param {string} key - character for key
     * @param {Array} modifiers
     * @param {string=} action passed in
     */
    function _pickBestAction(key, modifiers, action) {

        // if no action was picked in we should try to pick the one
        // that we think would work best for this key
        if (!action) {
            action = _getReverseMap()[key] ? 'keydown' : 'keypress';
        }

        // modifier keys don't work as expected with keypress,
        // switch to keydown
        if (action === 'keypress' && modifiers.length) {
            action = 'keydown';
        }

        return action;
    }

    /**
     * binds a key sequence to an event
     *
     * @param {string} combo - combo specified in bind call
     * @param {Array} keys
     * @param {Function} callback
     * @param {string=} action
     * @returns void
     */
    function _bindSequence(combo, keys, callback, action) {

        // start off by adding a sequence level record for this combination
        // and setting the level to 0
        _sequence_levels[combo] = 0;

        // if there is no action pick the best one for the first key
        // in the sequence
        if (!action) {
            action = _pickBestAction(keys[0], []);
        }

        /**
         * callback to increase the sequence level for this sequence and reset
         * all other sequences that were active
         *
         * @param {Event} e
         * @returns void
         */
        var _increaseSequence = function(e) {
                _inside_sequence = action;
                ++_sequence_levels[combo];
                _resetSequence();
            },

            /**
             * wraps the specified callback inside of another function in order
             * to reset all sequence counters as soon as this sequence is done
             *
             * @param {Event} e
             * @returns void
             */
            _callbackAndReset = function(e) {
                _callback(callback, e);

                // we should ignore the next key up if the action is key down
                // or keypress.  this is so if you finish a sequence and
                // release the key the final key will not trigger a keyup
                if (action !== 'keyup') {
                    _ignore_next_keyup = _characterFromEvent(e);
                }

                // weird race condition if a sequence ends with the key
                // another sequence begins with
                setTimeout(_resetSequences, 10);
            },
            i;

        // loop through keys one at a time and bind the appropriate callback
        // function.  for any key leading up to the final one it should
        // increase the sequence. after the final, it should reset all sequences
        for (i = 0; i < keys.length; ++i) {
            _bindSingle(keys[i], i < keys.length - 1 ? _increaseSequence : _callbackAndReset, action, combo, i);
        }
    }

    /**
     * binds a single keyboard combination
     *
     * @param {string} combination
     * @param {Function} callback
     * @param {string=} action
     * @param {string=} sequence_name - name of sequence if part of sequence
     * @param {number=} level - what part of the sequence the command is
     * @returns void
     */
    function _bindSingle(combination, callback, action, sequence_name, level) {

        // make sure multiple spaces in a row become a single space
        combination = combination.replace(/\s+/g, ' ');

        var sequence = combination.split(' '),
            i,
            key,
            keys,
            modifiers = [];

        // if this pattern is a sequence of keys then run through this method
        // to reprocess each pattern one key at a time
        if (sequence.length > 1) {
            return _bindSequence(combination, sequence, callback, action);
        }

        // take the keys from this pattern and figure out what the actual
        // pattern is all about
        keys = combination === '+' ? ['+'] : combination.split('+');

        for (i = 0; i < keys.length; ++i) {
            key = keys[i];

            // normalize key names
            if (_SPECIAL_ALIASES[key]) {
                key = _SPECIAL_ALIASES[key];
            }

            // if this is not a keypress event then we should
            // be smart about using shift keys
            // this will only work for US keyboards however
            if (action && action != 'keypress' && _SHIFT_MAP[key]) {
                key = _SHIFT_MAP[key];
                modifiers.push('shift');
            }

            // if this key is a modifier then add it to the list of modifiers
            if (_isModifier(key)) {
                modifiers.push(key);
            }
        }

        // depending on what the key combination is
        // we will try to pick the best event for it
        action = _pickBestAction(key, modifiers, action);

        // make sure to initialize array if this is the first time
        // a callback is added for this key
        if (!_callbacks[key]) {
            _callbacks[key] = [];
        }

        // remove an existing match if there is one
        _getMatches(key, modifiers, action, !sequence_name, combination);

        // add this call back to the array
        // if it is a sequence put it at the beginning
        // if not put it at the end
        //
        // this is important because the way these are processed expects
        // the sequence ones to come first
        _callbacks[key][sequence_name ? 'unshift' : 'push']({
            callback: callback,
            modifiers: modifiers,
            action: action,
            seq: sequence_name,
            level: level,
            combo: combination
        });
    }

    /**
     * binds multiple combinations to the same callback
     *
     * @param {Array} combinations
     * @param {Function} callback
     * @param {string|undefined} action
     * @returns void
     */
    function _bindMultiple(combinations, callback, action) {
        for (var i = 0; i < combinations.length; ++i) {
            _bindSingle(combinations[i], callback, action);
        }
    }

    // start!
    _addEvent(document, 'keypress', _handleKey);
    _addEvent(document, 'keydown', _handleKey);
    _addEvent(document, 'keyup', _handleKey);

    return {

        /**
         * binds an event to mousetrap
         *
         * can be a single key, a combination of keys separated with +,
         * a comma separated list of keys, an array of keys, or
         * a sequence of keys separated by spaces
         *
         * be sure to list the modifier keys first to make sure that the
         * correct key ends up getting bound (the last key in the pattern)
         *
         * @param {string|Array} keys
         * @param {Function} callback
         * @param {string=} action - 'keypress', 'keydown', or 'keyup'
         * @returns void
         */
        bind: function(keys, callback, action) {
            _bindMultiple(keys instanceof Array ? keys : [keys], callback, action);
            _direct_map[keys + ':' + action] = callback;
        },

        /**
         * unbinds an event to mousetrap
         *
         * the unbinding sets the callback function of the specified key combo
         * to an empty function and deletes the corresponding key in the
         * _direct_map dict.
         *
         * the keycombo+action has to be exactly the same as
         * it was defined in the bind method
         *
         * TODO: actually remove this from the _callbacks dictionary instead
         * of binding an empty function
         *
         * @param {string|Array} keys
         * @param {string} action
         * @returns void
         */
        unbind: function(keys, action) {
            if (_direct_map[keys + ':' + action]) {
                delete _direct_map[keys + ':' + action];
                this.bind(keys, function() {}, action);
            }
        },

        /**
         * triggers an event that has already been bound
         *
         * @param {string} keys
         * @param {string=} action
         * @returns void
         */
        trigger: function(keys, action) {
            _direct_map[keys + ':' + action]();
        },

        /**
         * resets the library back to its initial state.  this is useful
         * if you want to clear out the current keyboard shortcuts and bind
         * new ones - for example if you switch to another page
         *
         * @returns void
         */
        reset: function() {
            _callbacks = {};
            _direct_map = {};
        }
    };
}) ();