Info

I have an array, I want a new array where I do something to it, how do I do it fastest.

Preparation code

<script src="//raw.github.com/documentcloud/underscore/master/underscore-min.js">
</script>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>
<script>
  Benchmark.prototype.setup = function() {
    var _len = 10000;
    var a = new Array(_len);
    while (_len--) {
      a[_len] = _len;
    }
    var f = function(a) {
        return a * a;
        }
  };
</script>

Preparation code output

Test runner

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Java applet disabled.

var i = a.length;
var out = new Array(i);
while (i--) {
  out[i] = f(a[i]);
}

var i = a.length;
var out = new Array(i);
i--;
do {
  out[i] = f(a[i]);
}
while (i--);

var i = 0;
var len = a.length;
var out = [];
while (i !== len) {
  out.push(f(a[i]));
  i++
}

var i = 0;
var len = a.length;
var out = new Array(len);
while (i !== len) {
  out[i] = f(a[i]);
  i++
}

var i = 0;
var len = a.length;
var out = new Array(len);
while (i < len) {
  out[i] = f(a[i]);
  i++
}

var i = a.length;
var out = new Array(i);
for (; i--;) {
  out[i] = f(a[i]);
}

var len = a.length;
var out = new Array(len);
for (var i = 0; i !== len; i++) {
  out[i] = f(a[i]);
}

var len = a.length;
var out = new Array(len);
for (var i = 0; i < len; i++) {
  out[i] = f(a[i]);
}

var out = a.map(f);

var out = $.map(a, f);

var out = _.map(a, f);

var out = new Array(a.length);
a.forEach(function(v, i) {
  out[i] = f(v);
});

var i = 0;
var len = a.length;
var out = [];
while (i < len) {
  out[i] = f(a[i]);
  i++
}

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Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:

• Revision 1: published by cwmma on 8th March 2013
• Revision 2: published by Martijn Faassen on 8th March 2013
• Revision 3: published on 8th March 2013
• Revision 4: published on 9th March 2013
• Revision 5: published on 9th March 2013
• Revision 6: published on 12th March 2013
• Revision 7: published on 12th March 2013
• Revision 8: published on 25th March 2013
• Revision 9: published on 25th March 2013
• Revision 10: published on 25th March 2013
• Revision 12: published on 26th March 2013

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