mousetrap.js

/*global define:false */
/**
 * Copyright 2013 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
 *
 * @version 1.4.6
 * @url craig.is/killing/mice
 */
(function (root, document, factory) {
    if (typeof define === 'function' && define.amd) {
        // AMD. Register as an anonymous module.
        define([], function () {
            return (root.Mousetrap = factory(document));
        });
    } else if (typeof exports === 'object') {
        // Node. Does not work with strict CommonJS, but
        // only CommonJS-like environments that support module.exports,
        // like Node.
        module.exports = factory(document);
    } else {
        // Browser globals
        root.Mousetrap = factory(document);
    }
}(this, document, function (document) {

    /**
     * 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 in case 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 equivalents
         *
         * this is so you can use keyup events with these keys
         *
         * note that this will only work reliably 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',
            'mod': /Mac|iPod|iPhone|iPad/.test(navigator.platform) ? 'meta' : 'ctrl'
        },

        /**
         * 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 = {},

        /**
         * a stack of lists of callbacks, to be used via Mousetrap.save() and Mousetrap.restore
         *
         * @type {Array}
         */
        _callbacksStack = [],

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

        /**
         * a stack of lists of direct maps, to be used via Mousetrap.save() and Mousetrap.restore
         *
         * @type {Array}
         */
        _directMapStack = [],

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

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

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

        /**
         * temporary state where we will ignore the next keypress
         *
         * @type {boolean}
         */
        _ignoreNextKeypress = false,

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

        /**
         * set the delay between keypresses to a number in ms
         *
         * @type {number}
         */
        _keySequenceDelay = 1000;

    /**
     * loop through the f keys, f1 to f24 and add them to the map
     * programmatically
     */
    for (var i = 1; i <= 24; ++i) {
        _MAP[111 + i] = 'f' + i;
    }

    /**
     * loop through to map numbers on the numeric keypad
     */
    for (i = 0; i <= 9; ++i) {
        _MAP[i + 96] = i;
    }

    /**
     * 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) {
            object.addEventListener(type, callback, false);
            return;
        }

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

    /**
     * takes the event and returns the key character
     *
     * @param {Event} e
     * @return {string}
     */
    function _characterFromEvent(e) {
        // for keypress events we should return the character as is
        if (e.type === 'keypress') {
            var character = String.fromCharCode(e.which);

            // if the shift key is not pressed then it is safe to assume
            // that we want the character to be lowercase.  this means if
            // you accidentally have caps lock on then your key bindings
            // will continue to work
            //
            // the only side effect that might not be desired is if you
            // bind something like 'A' cause you want to trigger an
            // event when capital A is pressed caps lock will no longer
            // trigger the event.  shift+a will though.
            if (!e.shiftKey) {
                character = character.toLowerCase();
            }

            return character;
        }

        // 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

        // with keydown and keyup events the character seems to always
        // come in as an uppercase character whether you are pressing shift
        // or not.  we should make sure it is always lowercase for comparisons
        return String.fromCharCode(e.which).toLowerCase();
    }

    /**
     * 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} doNotReset
     * @returns void
     */
    function _resetSequences(doNotReset) {
        doNotReset = doNotReset || {};

        var activeSequences = false,
            key;

        for (key in _sequenceLevels) {
            if (doNotReset[key]) {
                activeSequences = true;
                continue;
            }
            _sequenceLevels[key] = 0;
        }

        if (!activeSequences) {
            _nextExpectedAction = false;
        }
    }

    /**
     * finds all callbacks that match based on the keycode, modifiers,
     * and action
     *
     * @param {string} character
     * @param {Array} modifiers
     * @param {Event|Object} e
     * @param {string=} sequenceName - name of the sequence we are looking for
     * @param {string=} combination
     * @param {number=} level
     * @returns {Array}
     */
    function _getMatches(character, modifiers, e, sequenceName, combination, level) {
        var i,
            callback,
            matches = [],
            action = e.type;

        // 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 a sequence name is not specified, but this is a sequence at
            // the wrong level then move onto the next match
            if (!sequenceName && callback.seq && _sequenceLevels[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 and the meta key and control key
            // are not pressed that means that we need to only look at the
            // character, otherwise check the modifiers as well
            //
            // chrome will not fire a keypress if meta or control is down
            // safari will fire a keypress if meta or meta+shift is down
            // firefox will fire a keypress if meta or control is down
            if ((action === 'keypress' && !e.metaKey && !e.ctrlKey) || _modifiersMatch(modifiers, callback.modifiers)) {

                // when you bind a combination or sequence a second time it
                // should overwrite the first one.  if a sequenceName or
                // combination is specified in this call it does just that
                //
                // @todo make deleting its own method?
                var deleteCombo = !sequenceName && callback.combo === combination;
                var deleteSequence = sequenceName && callback.seq === sequenceName && callback.level === level;
                if (deleteCombo || deleteSequence) {
                    _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;
    }

    /**
     * prevents default for this event
     *
     * @param {Event} e
     * @returns void
     */
    function _preventDefault(e) {
        if (e.preventDefault) {
            e.preventDefault();
            return;
        }

        e.returnValue = false;
    }

    /**
     * stops propagation for this event
     *
     * @param {Event} e
     * @returns void
     */
    function _stopPropagation(e) {
        if (e.stopPropagation) {
            e.stopPropagation();
            return;
        }

        e.cancelBubble = true;
    }

    /**
     * actually calls the callback function
     *
     * if your callback function returns false this will use the jquery
     * convention - prevent default and stop propagation on the event
     *
     * @param {Function} callback
     * @param {Event} e
     * @returns void
     */
    function _fireCallback(callback, e, combo, sequence) {

        // if this event should not happen stop here
        if (Mousetrap.stopCallback(e, e.target || e.srcElement, combo, sequence)) {
            return;
        }

        if (callback(e, combo) === false) {
            _preventDefault(e);
            _stopPropagation(e);
        }
    }

    /**
     * handles a character key event
     *
     * @param {string} character
     * @param {Array} modifiers
     * @param {Event} e
     * @returns void
     */
    function _handleKey(character, modifiers, e) {
        var callbacks = _getMatches(character, modifiers, e),
            i,
            doNotReset = {},
            maxLevel = 0,
            processedSequenceCallback = false;

        // Calculate the maxLevel for sequences so we can only execute the longest callback sequence
        for (i = 0; i < callbacks.length; ++i) {
            if (callbacks[i].seq) {
                maxLevel = Math.max(maxLevel, callbacks[i].level);
            }
        }

        // 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) {

                // only fire callbacks for the maxLevel to prevent
                // subsequences from also firing
                //
                // for example 'a option b' should not cause 'option b' to fire
                // even though 'option b' is part of the other sequence
                //
                // any sequences that do not match here will be discarded
                // below by the _resetSequences call
                if (callbacks[i].level !== maxLevel) {
                    continue;
                }

                processedSequenceCallback = true;

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

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

        // if the key you pressed matches the type of sequence without
        // being a modifier (i.e. "keyup" or "keypress") then we should
        // reset all sequences that were not matched by this event
        //
        // this is so, for example, if you have the sequence "h a t" and you
        // type "h e a r t" it does not match.  in this case the "e" will
        // cause the sequence to reset
        //
        // modifier keys are ignored because you can have a sequence
        // that contains modifiers such as "enter ctrl+space" and in most
        // cases the modifier key will be pressed before the next key
        //
        // also if you have a sequence such as "ctrl+b a" then pressing the
        // "b" key will trigger a "keypress" and a "keydown"
        //
        // the "keydown" is expected when there is a modifier, but the
        // "keypress" ends up matching the _nextExpectedAction since it occurs
        // after and that causes the sequence to reset
        //
        // we ignore keypresses in a sequence that directly follow a keydown
        // for the same character
        var ignoreThisKeypress = e.type === 'keypress' && _ignoreNextKeypress;
        if (e.type === _nextExpectedAction && !_isModifier(character) && !ignoreThisKeypress) {
            _resetSequences(doNotReset);
        }

        _ignoreNextKeypress = processedSequenceCallback && e.type === 'keydown';
    }

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

        // normalize e.which for key events
        // @see http://stackoverflow.com/questions/4285627/javascript-keycode-vs-charcode-utter-confusion
        if (typeof e.which !== 'number') {
            e.which = e.keyCode;
        }

        var character = _characterFromEvent(e);

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

        // need to use === for the character check because the character can be 0
        if (e.type === 'keyup' && _ignoreNextKeyup === character) {
            _ignoreNextKeyup = false;
            return;
        }

        Mousetrap.handleKey(character, _eventModifiers(e), 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 {_keySequenceDelay} 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 _resetSequenceTimer() {
        clearTimeout(_resetTimer);
        _resetTimer = setTimeout(_resetSequences, _keySequenceDelay);
    }

    /**
     * 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 numeric 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
        _sequenceLevels[combo] = 0;

        /**
         * callback to increase the sequence level for this sequence and reset
         * all other sequences that were active
         *
         * @param {string} nextAction
         * @returns {Function}
         */
        function _increaseSequence(nextAction) {
            return function() {
                _nextExpectedAction = nextAction;
                ++_sequenceLevels[combo];
                _resetSequenceTimer();
            };
        }

        /**
         * 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
         */
        function _callbackAndReset(e) {
            _fireCallback(callback, e, combo);

            // 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') {
                _ignoreNextKeyup = _characterFromEvent(e);
            }

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

        // 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
        //
        // if an action is specified in the original bind call then that will
        // be used throughout.  otherwise we will pass the action that the
        // next key in the sequence should match.  this allows a sequence
        // to mix and match keypress and keydown events depending on which
        // ones are better suited to the key provided
        for (var i = 0; i < keys.length; ++i) {
            var isFinal = i + 1 === keys.length;
            var wrappedCallback = isFinal ? _callbackAndReset : _increaseSequence(action || _getKeyInfo(keys[i + 1]).action);
            _bindSingle(keys[i], wrappedCallback, action, combo, i);
        }
    }

    /**
     * Converts from a string key combination to an array
     *
     * @param  {string} combination like "command+shift+l"
     * @return {Array}
     */
    function _keysFromString(combination) {
        var a = combination.split('+');
        // cope with both "+" and combo's like "shift+ctrl++"
        var end = a.length - 1;
        if (end > 0 && a[end] === "") {
            a.pop();
            end--;
        }
        for (var i = 0; i <= end; i++) {
            if (a[i] === "") {
                a[i] = "+";
            }
        }
        return a;
    }

    /**
     * Gets info for a specific key combination
     *
     * @param  {string} combination key combination ("command+s" or "a" or "*")
     * @param  {string=} action
     * @returns {Object}
     */
    function _getKeyInfo(combination, action) {
        var keys,
            key,
            i,
            modifiers = [];

        // take the keys from this pattern and figure out what the actual
        // pattern is all about
        keys = _keysFromString(combination);

        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);

        return {
            key: key,
            modifiers: modifiers,
            action: action
        };
    }

    /**
     * binds a single keyboard combination
     *
     * @param {string} combination
     * @param {Function} callback
     * @param {string=} action
     * @param {string=} sequenceName - 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, sequenceName, level) {

        // store a direct mapped reference for use with Mousetrap.trigger
        _directMap[combination + ':' + action] = callback;

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

        var sequence = combination.split(' '),
            info;

        // 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) {
            _bindSequence(combination, sequence, callback, action);
            return;
        }

        info = _getKeyInfo(combination, action);

        // make sure to initialize array if this is the first time
        // a callback is added for this key
        _callbacks[info.key] = _callbacks[info.key] || [];

        // remove an existing match if there is one
        _getMatches(info.key, info.modifiers, {type: info.action}, sequenceName, combination, level);

        // 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[info.key][sequenceName ? 'unshift' : 'push']({
            callback: callback,
            modifiers: info.modifiers,
            action: info.action,
            seq: sequenceName,
            level: level,
            combo: combination
        });
    }

    /**
     * binds multiple combinations to the same callback
     *
     * @param {Array} combinations
     * @param {Function} callback
     * @param {string|undefined} action
     * @param {number|undefined} timeout maximum allowed delay until the next key. Note that this will replace the Mousetrap global key delay timeout.
     * @returns void
     */
    function _bindMultiple(combinations, callback, action, timeout) {
        if (timeout != null) {
            // only set the timeout when an actual value was provided:
            Mousetrap.setKeySequenceDelay(timeout);
        }
        for (var i = 0; i < combinations.length; ++i) {
            _bindSingle(combinations[i], callback, action);
        }
    }

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

    var Mousetrap = {

        /**
         * binds an event to mousetrap
         *
         * can be a single key, a combination of keys separated with +,
         * 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, timeout) {
            keys = keys instanceof Array ? keys : [keys];
            _bindMultiple(keys, callback, action, timeout);
            return this;
        },

        /**
         * 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
         * _directMap dict.
         *
         * TODO: actually remove this from the _callbacks dictionary instead
         * of binding an empty function
         *
         * the keycombo+action has to be exactly the same as
         * it was defined in the bind method
         *
         * @param {string|Array} keys
         * @param {string} action
         * @returns void
         */
        unbind: function(keys, action) {
            return Mousetrap.bind(keys, function() {}, action);
        },

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

        /**
         * 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 = {};
            _directMap = {};
            return this;
        },

        /**
         * saves the current state of the library in a stack fashion.  this is useful
         * if you want to clear out the current keyboard shortcuts and bind
         * new ones but are interested in recovering the previous
         * state after - for example if you are showing some sort of modal dialog
         *
         * @returns void
         */
        save: function() {
            _callbacksStack.push(_callbacks);
            _directMapStack.push(_directMap);
            _callbacks = {};
            _directMap = {};
            return this;
        },

        /**
         * restores the current state of the library in a stack fashion.  this is useful
         * if you want to clear out the current keyboard shortcuts and bind
         * new ones but are interested in recovering the previous
         * state after - for example if you are showing some sort of modal dialog
         *
         * @returns void
         */
        restore: function() {
            if ((_callbacksStack.length > 0) && (_directMapStack.length > 0)) {
                _callbacks = _callbacksStack.pop();
                _directMap = _directMapStack.pop();
            }
            return this;
        },

        /**
         * returns defined callback for specific keys 
         *
         * @param {String/Array} keys
         * @param {String} action
         * @returns {Function} callback for keys
         */
        getCallback: function(keys, action)
        {
            return _directMap[keys + ':' + action];
        },

        /**
         * should we stop this event before firing off callbacks?
         *
         * @param {Event} e
         * @param {Element} element
         * @return {boolean}
         */
        stopCallback: function(e, element) {
            // 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 element.tagName == 'INPUT' || element.tagName == 'SELECT' || element.tagName == 'TEXTAREA' || element.tagName == 'OBJECT' || element.tagName == 'EMBED' || element.isContentEditable;
        },

        /**
         * sets the delay between recognized keypresses in a sequence
         *
         * @param {Number} timeout in milliseconds. When set to zero (null or other 'falsey' JS value) the default value of 1000 (1 second) is restored.
         * @returns void
         */
        setKeySequenceDelay: function(timeout) {
            if (!timeout) {
                _keySequenceDelay = 1000;
            } else if (timeout > 10) {
                _keySequenceDelay = timeout;
            } else {
                throw "Mousetrap: Unable to set timeout to " + timeout;
            }
        },

        /**
         * exposes _handleKey publicly so it can be overwritten by extensions
         */
        handleKey: _handleKey,
        
        getMap: function() {
          return _MAP;
        },
        
        getReverseMap: function() {
            return _getReverseMap();
        },
        
        getKeycodeMap: function() {
          return _KEYCODE_MAP;
        },
        
        getShiftMap: function() {
          return _SHIFT_MAP;
        }
    };

    // expose mousetrap to the global object
    return Mousetrap;
}));