Fastest array loops in Javascript

JavaScript performance comparison

Revision 518 of this test case created by

Preparation code

<script>
  // Populate the base array
  var sum = 0;
  var arr = [], newArr = [];
  for (var i = 0; i < 1000; i++) {
    arr[i] = i;
  }

  function someFn(ix) {
    sum = sum + ix * 5 + 1 / 3 * 8;
  }
   
  function recurse(i)
  {
    var t = arr.length+i;
   if(i <= arr.length)
    recurse(++i);
  }
</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++) {
  var t = arr.length + i;
}
pending…
While loop, basic
var i = 0;
while (i < arr.length) {
  var t = arr.length + i;
  i++;
}
pending…
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
  var t = arr.length + i;
}
pending…
For loop, i--
for (var i = arr.length; i > 0; i--) {
  var t = arr.length + i;
}
pending…
Do-while loop, i--
var i = arr.length - 1;
do {
  var t = arr.length + i;
}
while (i--);
pending…
Do-while loop, --i
var i = arr.length;
if (i > 0) {
  do {
    var t = arr.length + i;
  }
  while (--i);
}
pending…
For..in loop
for (var i in arr) {
  var t = arr.length + i;
}
pending…
Order
while (i = arr.shift()) {
  var t = arr.length + i;
}
console.log(sum);
pending…
forEach
arr.forEach(function(v) {
  var t = arr.length + i;
})
pending…
order validation
while ((i = arr.shift()) !== undefined) {
  var t = arr.length + i;
}
pending…
While ! Undefined
var a;
while ((a = arr[i++]) !== undefined) {
  var t = arr.length + i;
}
pending…
Pop
while (i = arr.pop()) {
  var t = arr.length + i;
  newArr.push(i);
}
pending…
Order w/ array copy
var copy = arr.slice(0);
while (i = copy.shift()) {
  var t = arr.length + i;
}
pending…
Pop w/ reverse()
arr.reverse();
while (i = arr.pop()) {
  var t = arr.length + i;
  newArr.push(i);
}
pending…
recursive
recurse(0);
pending…

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Revisions

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