Loops

JavaScript performance comparison

Revision 128 of this test case created by ASM

Preparation code


      
      <script>
Benchmark.prototype.setup = function() {
  var arr = [];
  var obj = {};
  for( var i = 0; i < 40; i++ ) {
      arr[ i ] = i+1;
      obj[ i ] = i+1;
  }
  
  // to let IE7 && other old browsers run this as well
  if (!Array.prototype.forEach)
  {
    Array.prototype.forEach = function(fun)
    {
      var len = this.length;
      for (var i = 0; i < len; ++i)
          fun(this[i]);
    };
  }

};
</script>

Test runner

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Java applet disabled.

Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
01) Old ’n’ busted for
for (var i = 0; i < arr.length; ++i) {
  arr[i];
};
pending…
02) Old ’n’ busted + length caching
for (var i = 0, len = arr.length; i < len; ++i) {
  arr[i];
};
pending…
03) Old ’n’ busted + var outside loop
var len = arr.length;
for (var i = 0; i < len; ++i ) {
  arr[ i ];
};
pending…
04) Reverse for
for (var i = arr.length; i--;) {
  arr[i];
};
pending…
05) while loop
var i = 0;
while (i < arr.length) {
  arr[i];
  i++;
};
pending…
06) while loop + length caching
var i = 0,
  len = arr.length;
while (i < len) {
  arr[i];
  i++;
};
pending…
07) Reverse while
var i = arr.length;
while (i--) {
  arr[i];
};
pending…
08) Reverse do … while loop
var i = arr.length;
do {
  arr[i];
} while (i--);
pending…
09) Cool guy loop + length caching
for (var i = -1, len = arr.length; ++i < len;) {
  arr[i];
};
pending…
10) Native forEach
arr.forEach(function(x) {
  x;
});
pending…
11) Native forEach with named function
function foo(x) {
  x;
};
arr.forEach(foo);
pending…
12) For In Array
for (i in arr) {
  arr[i];
};
pending…
13) For In Object
for (i in obj) {
  obj[i];
};
pending…
14) Object Property Accessor using Bracket notation
for( var i = 0; arr[i]; i++) {
  arr[i];
};
pending…

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Revisions

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