jQuery.fn.each vs. jQuery.fn.quickEach

JavaScript performance comparison

Revision 77 of this test case created

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.

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;
    };
  }());
</script>

Preparation code output

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Testing in unknown unknown
Test Ops/sec
.each()
a.each(function() {
  this; //dom object
});
pending…
.quickEach()
a.quickEach(function() {
  this[0]; //dom object
});
pending…

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Revisions

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