jQuery.fn.each vs. jQuery.fn.quickEach vs. Prototype Array.each usecase only

JavaScript performance comparison

Revision 30 of this test case created by Erwan Legrand

Info

The quickEach method will pass a non-unique jQuery instance to the callback meaning that there will be no need to instantiate a fresh jQuery instance on each iteration. Most of the slow-down inherent in jQuery’s native iterator method (each) is the constant need to have access to jQuery’s methods, and so most developers see constructing multiple instances as no issue… A better approach would be quickEach.

Further added the each implementation from the Prototype library (with a small variation) which yields better results, because when available it will use the browser Array.each implementation.

Preparation code

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>

<script>
  var a = $('<div/>').append(Array(100).join('<a></a>')).find('a');
  
  jQuery.fn.quickEach = (function() {
   var jq = jQuery([1]);
   return function(c) {
    var i = -1,
        el, len = this.length;
    try {
     while (++i < len && (el = jq[0] = this[i]) && c.call(jq, i, el) !== false);
    } catch (e) {
     delete jq[0];
     throw e;
    }
    delete jq[0];
    return this;
   };
  }());
  
  // The Prototype library Array.each implementation
  jQuery.fn.prototypeEach = (function() {
   var arrayProto = Array.prototype,
       slice = arrayProto.slice,
       _each = arrayProto.forEach;
  
   return !!_each ? _each : function(iterator, context) {
    for (var i = 0, length = this.length >>> 0; i < length; i++) {
     if (i in this) iterator.call(context, this[i], i, this);
    }
   }
  })();
  
    // My each2 plugin
    (function($) {
     var jq = $([]);
     $.fn.each2 = function(fn) {
      var i = -1,
          elem;
      while ((elem = jq[0] = this[++i]) && fn.call(elem, i, jq) !== false) {}
      return this;
     };
    })(jQuery);
</script>

Preparation code output

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Testing in unknown unknown
Test Ops/sec
.each()
 
a.each(function() {
 $(this).css('width','1px');
});
 pending…
.quickEach()
 
a.quickEach(function() {
 this.css('width','1px');
});
 pending…
.prototypeEach()
 
a.prototypeEach(function() {
 this.css('width','1px');
}, jQuery());
 pending…
.each2()
 
a.each2(function(i, jq) {
 jq.css('width','1px');
});
 pending…
for loop
 
for (var i = 0, l = a.length; i < l; i++) {
    a[i].style.width = '1px';
}
 pending…

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Revisions

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