object-looping

JavaScript performance comparison

Revision 2 of this test case created by Jonathan Perry

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var obj = {
      a: 1,
      b: 2,
      c: 3,
      d: 4,
      f: 5
    },
    i = 0,
    _hasOwnProperty = Object.prototype.hasOwnProperty,
    value = null,
    keys = Object.keys(obj)
   
    function each (obj, fn) {
      var key;
      for (key in obj) {
        if (_hasOwnProperty.call(obj, key)){
          fn.call(obj, obj[key])
        }
      }
    }
   
    function each2 (obj, fn) {
        var keys = Object.keys(obj)
        for (var i=0, key; key = keys[i++]; fn.call(obj, key, obj[key]));
    }
   
    function withEach(key) {
       value = obj[key];
    }
};
</script>

Test runner

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Testing in unknown unknown
Test Ops/sec
for in, if
for (key in obj) {
  if (_hasOwnProperty.call(obj, key)) {
     value = obj[key];
  }
}
pending…
for in, continue
for (key in obj) {
  if (!_hasOwnProperty.call(obj, key)) {
    continue;
  } else {
    value = obj[key];
  }
}
pending…
Object.keys()
Object.keys(obj).forEach(withEach);
pending…
Object.keys() cached
keys.forEach(withEach);
pending…
Keys for;
for (var keys = Object.keys(obj), i = 0, ln = keys.length; i < ln; i++) {
    value = obj[key];
}
pending…
each, for in
each(obj, function (value) { });
pending…
for in, if (=== true)
for (key in obj) {
  if (_hasOwnProperty.call(obj, key) === true) {
     value = obj[key];
  }
}
pending…
for in, continue (!== true)
for (key in obj) {
  if (_hasOwnProperty.call(obj, key) !== true) {
    continue;
  } else {
    value = obj[key];
  }
}
pending…

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