Function _bindSequence

client/vendors/mousetrap.js:657–714

* 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

(combo, keys, callback, 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);
        }
    }