Adding and removing listeners-part-2

Benchmark created by David Mark on September 22, 2011

Description

Preparation HTML

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script>
/*
 * Context here is an HTML5 document
 * Appropriate build for this context would exclude XHTML support
 * Next line asserts document will create an HTML DOM
 * There are virtually no documents on the Web that create an XHTML DOM
 *
 */
var API = { disableXmlParseMode:true };
</script>
<script src="//www.cinsoft.net/mylib099-min.js"></script>
<script>
  // For My Library test
  
  var attachListener = API.attachListener;
  var detachListener = API.detachListener;
  
  // For cross-browser test
  
  // Degrades in browsers lacking native bind method (many)
  // Alternatively, use Function.prototype.call (adds back most of non-IE)
  // No frames - one document only
  
  var attachEventListener, removeAttachedEventListener;
  var elHtml = document.documentElement;
  
  if (elHtml) { // Need HTML element for feature detection
  
    // NOTE: Should use isHostMethod for host method detection
  
    if (elHtml.addEventListener && Function.prototype.bind) {
      attachEventListener = function(el, eventType, fn, thisObject) {
        var boundFunction = fn.bind(thisObject || el);
  
        el.addEventListener(eventType, boundFunction, false);
        return boundFunction; // NOTE: returns bound function for removal
      };
      removeAttachedEventListener = function(el, eventType, fn) {
        el.removeEventListener(eventType, fn);
      };
    } else if (elHtml.attachEvent && Function.prototype.call) {
  
      // Degrades under IE 5.5
  
      // NOTE: As written for test, all variables are global.
      // Wrap the whole thing in a "module" function and leaks will
      // be reintroduced. The "theseObjects" variable must be global
      // or a property of a global object (e.g. a "namespace" object).
  
      // Stores references to objects used for - this - object in listeners
  
      var theseObjects = [];
  
      // Index for theseObjects array, bumped on each attachment
  
      var theseObjectsIndex = 0;
  
      attachEventListener = function(el, eventType, fn, thisObject) {
        var thisObjectIndex = theseObjectsIndex++;
  
        // Store reference to object used for - this - in listener
  
        theseObjects[thisObjectIndex] = thisObject || el;
  
        var boundFunction = function() {
          fn.call(theseObjects[thisObjectIndex], window.event);
        };
  
        el.attachEvent('on' + eventType, boundFunction);
  
        // Discard unneeded references
        // Prevents circular references with host objects (e.g. the element)
        // Prevents IE leaks related to such circular references
        // No unload event cleanup required
  
        thisObject = el = null;
  
        return boundFunction;
      };
  
      removeAttachedEventListener = function(el, eventType, fn) {
        el.detachEvent('on' + eventType, fn);
      };
    }
  }
  
  // For all tests
  
  var el1 = document.createElement('div');
  var el2 = document.createElement('div');
  var el3 = document.createElement('div');
  var el4 = document.createElement('div');
  
  var listenerFunction = function() {
    var x = 1;
  };
  
  var thisObject = {};
</script>

Test runner

attachListener(el1, 'click', listenerFunction, thisObject);
detachListener(el1, 'click', listenerFunction);

E(el2).on('click', listenerFunction, thisObject).off('click', listenerFunction);

jQuery(el3).bind('click', jQuery.proxy(listenerFunction, thisObject)).unbind('click', jQuery.proxy(listenerFunction, thisObject));

// Apparently the only way to do this in one chain :(
// Breaking it in two or three wouldn't be in the spirit of jQuery.

if (attachEventListener) { // Conditionally defined
  removeAttachedEventListener(el4, 'click', attachEventListener(el4, 'click', listenerFunction, thisObject));
} else {
  throw new Error('Abort due to degraded browser');
}

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.

• Revision 1: published by David Mark on September 22, 2011