Fastest array loops in Javascript

JavaScript performance comparison

Revision 118 of this test case created by

Preparation code


      
      <script>
Benchmark.prototype.setup = function() {
  // Populate the base array
  var arr = [];
  for (var i = 0; i < 1000; i++) {
    arr[i] = i;
  }
  
  function someFn(ix) {
    return ix << 1;
  }
  var len = arr.length, i = 0;

};

Benchmark.prototype.teardown = function() {
  i = 0;

};
</script>

Test runner

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
For loop, basic
for (var i = 0; i < arr.length; i++) {
  someFn(arr[i]);
}
pending…
While loop, basic
while (i < len) {
  someFn(arr[i]);
  i++;
}
pending…
For loop, cached+init
for (var i = 0; i < len; i++) {
  someFn(arr[i]);
}
pending…
For loop, i--
for (var i = len; i > 0; i--) {
  someFn(arr[i]);
}
pending…
Do-while loop, i--
var i = len - 1;
do {
  someFn(arr[i]);
} while (i > len);
pending…
For..in loop
for (var i in arr) {
  someFn(arr[i]);
}
pending…
Order
while (i = arr.shift()) {
  someFn(arr[i]);
}
pending…
forEach
arr.forEach(function(v) {
  someFn(arr[v]);
})
pending…
order validation
while ((i = arr.shift()) !== undefined) {
  someFn(arr[i]);
}
pending…
While ! Undefined
var a;
while ((a = arr[i++]) !== undefined) {
  someFn(arr[a]);
}
pending…
Pop
while ((i = arr.pop()) !== undefined) {
  someFn(arr[i]);
}
pending…
Order w/ array copy
var copy = arr.slice(0);
while (i = copy.shift()) {
  someFn(arr[i]);
}
pending…
pop2
while (i !== undefined) {
  someFn(arr[i]);
  i = arr.pop();
}
pending…
non-init for
for (; i < len; ++i) {
  someFn(arr[i]);
}
pending…
Object.keys
Object.keys(arr).forEach(function(v) {
	someFn(arr[v]);
});
pending…
while non cached len
while (i < arr.length) {
  someFn(arr[i]);
  i++;
}
pending…

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Revisions

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