Backbone View mixin to handle keyboard events.

keyable.js

/**
* View mixin to handle keyboard events.
* It requires patching for method overrides.
*
* @example
* var KeyedView = Backbone.View.extend({});
* mixer.patch(KeyedView.prototype, keyable);
*
* var keyedView = new KeyedView({
*   keyboardEvents: {
*     'mod+s': function(e){ console.log('Save!')}
*   },
*   ...
* });
*
* Borrowed heavily from:
* https://github.com/elasticsales/backbone.mousetrap/blob/master/backbone.mousetrap.js
* 
* Modified/Forked to support:
* - AMD
* - mixer.patch instead of direct monkey patching
*
**/
define(function(require){
  var Mousetrap = require('mousetrap')
    , lodash = require('underscore');

  // Map from keyboard commands to the View instance that most recently bound each one.
  // so we can avoid accidentally unbinding keys when a view replaced a previous view's keybinding.
  var lastBound = {};

  return {
    keyboardEvents: {},
    bindKeyboardEvents: function(events){
      if (!(events || (events = lodash.result(this, 'keyboardEvents')))) return;
      for (var key in events) {
        var method = events[key];
        if (!lodash.isFunction(method)) method = this[events[key]];
        if (!method) throw new Error('Method "' + events[key] + '" does not exist');
        method = lodash.bind(method, this);

        // Use global-bind plugin when appropriate
        // https://github.com/ccampbell/mousetrap/tree/master/plugins/global-bind
        if ('bindGlobal' in Mousetrap && (key.indexOf('mod') !== -1 || key.indexOf('command') !== -1 || key.indexOf('ctrl') !== -1)) {
          Mousetrap.bindGlobal(key, method);
        } else {
          Mousetrap.bind(key, method);
        }
        lastBound[key] = this;
      }
      return this;
    },

    unbindKeyboardEvents: function() {
      for (var keys in this.keyboardEvents) {
        if (lastBound[keys] === this) {
          Mousetrap.unbind(keys);
          delete lastBound[keys];
        }
      }
      return this;
    },

    delegateEvents: function() {
      return this.bindKeyboardEvents();
    },

    undelegateEvents: function() {
      return this.unbindKeyboardEvents();
    },

    remove: function() {
      return this.unbindKeyboardEvents();
    }
  }

});