Extension of dojo/on to toggle 2 event handlers

onswitchable.js

/*global define*/
/*jshint laxcomma:true*/
define([
  'dojo/on'
], function(on) {
  'use strict';

  var _on = on;

  _on.switchable = function(target, type, listener1, listener2) {
    var funcs
      , index
      , currentListener
      , signal;

    funcs = [listener1, listener2];
    index = 0;
    currentListener = funcs[index];
    signal = _on(target, type, function() {
      return currentListener.apply(this, arguments);
    });

    signal.toggle = function() {
      index = 1 - index;
      currentListener = funcs[index];
    };

    return signal;
  };

  return _on;

});