for vs forEach, including uncached length for worst-case

JavaScript performance comparison

Revision 203 of this test case created by

Preparation code

<script src="https://code.jquery.com/jquery-2.1.1.min.js">
</script>
      
<script>
Benchmark.prototype.setup = function() {
  var i,
    value,
    length,
    values = [],
    sum = 0,
    context = values;
  
  
  for (i = 0; i < 10000; i++) {
    values[i] = Math.random();
  }
  
  function add(val) {
    sum += val;
  }
  
  function addEach(k, val) {
    sum += val;
  }
  
  var toString = Object.prototype.toString;
  
  function isArray(obj) {
    return toString.call(obj) === '[object Array]';
  }
  
  function isObject(obj) {
    return toString.call(obj) === '[object Object]';
  }
  
  function isString(obj) {
    return toString.call(obj) === '[object String]';
  }
  
  function each(obj, iterator) {
    var key, length;
    if (!obj) {
      return;
    }
    length = obj.length;
  
    if (isArray(obj) || isString(obj)) {
      for (key = 0; key < length; key += 1) {
        iterator(obj[key], key, obj);
      }
      return obj;
    }
  
    if (isObject(obj)) {
      for (key in obj) {
        if (obj.hasOwnProperty(key)) {
          iterator(obj[key], key, obj);
        }
      }
      return obj;
    }
  
    return obj;
  };

};

Benchmark.prototype.teardown = function() {
  i = 0;
  value = 0;
  length = 0;
  values = [];
  sum = 0;

};
</script>

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
forEach
values.forEach(add);
pending…
for loop, cached length, callback
var arr = values,
  length = arr.length;
for (var i = 0; i < length; i++) {
  add(arr[i], i, arr);
}
pending…
for loop, cached length, callback.call
length = values.length;
for (i = 0; i < length; i++) {
  add.call(context, values[i], i, values);
}
pending…
$.each
$.each(values, addEach);
pending…
for loop, assignment condition, callback
for (i = 0;
  (value = values[i]) !== undefined; i++) {
  add(value, i, values);
}
pending…
for loop, assignment condition, callback.call
for (i = 0;
  (value = values[i]) !== undefined; i++) {
  add.call(context, value, i, values);
}
pending…
native map function
values.map(add);
pending…
new each
each(values, add);
pending…
for loop, un-cached length, callback
var arr = values;
for (var i = 0; i < arr.length; i++) {
  add(arr[i], i, arr);
}
pending…
for loop, cached length in loop,
var arr = values;
for (var i = 0, n = arr.length; i < n; i++) {
  add(arr[i], i, arr);
}
pending…

Compare results of other browsers

Revisions

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

0 Comments