jQuery.each vs. for loop

JavaScript performance comparison

Revision 162 of this test case created by Paul Grenier and last updated

Preparation code

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>
<script>
  var a = $('*').get(),
      e;
  //https://gist.github.com/4081985
  var each = (function() {
    function each(arr, fn) {
      var len = arr.length;
      return (each[len] || (each[len] = each.factory(len), each[len]))(arr, fn);
    }
    each.factory = function(len) {
      var body = "\tvar i = 0;\n";
      while (len--) {
        body += "\tfn(i, arr[i++]);\n";
      }
      body += "\treturn;\n";
      return Function("arr", "fn", body);
    };
    return each;
  }());
</script>

Preparation code output

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Testing in unknown unknown
Test Ops/sec
jQuery.each
 
$.each(a, function(index, element) {
  e = element;
});
 pending…
for loop
 
for (var i = 0, len = a.length; i < len; i++) {
  e = a[i];
};
 pending…
for without caching
 
for (var i = 0; i < a.length; i++) {
  e = a[i];
};
 pending…
alternative for loop
 
for (var i in a) {
  e = a[i];
};
 pending…
reverse for
 
for (var i = a.length; i--;) {
  e = a[i];
}
 pending…
reverse while
 
var i = a.length
while (i--) {
  e = a[i];
}
 pending…
foreach
 
a.forEach(function(elem) {
  e = elem;
});
 pending…
reverse for, forward index
 
for (var i = a.length, end = i - 1; i--;) {
  e = a[end - i];
}
 pending…
anti-loop
 
each(a, function(i, elem) {
  e = elem;
});
 pending…
for loop variant 1
 
for (var i = -1, n = a.length; ++i < n;) {
  e = a[i];
}
 pending…
for loop variant 2
 
for (var item, i = -1; item = a[++i];) {
  e = item;
}
 pending…

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