Fastest array loops in Javascript (v262)

Revision 262 of this benchmark created by test1212312 on

Preparation HTML

<script>
  function someFn(ix) {
    try { 
        ix += 1; 
        if (ix < 0) {
           throw new Error('e');
        }
    } catch (e){
        alert(e);
    }
    return ix * 5 + 1 / 3 * 8;
  }
</script>

Setup

// Populate the base array
    var arr = [],
      a, i, len, arr2 = [];
    for (i = 0; i < 1000; i++) {
      arr[i] = i + 1;
    }
  Array.prototype.each = function (c) {
      var l = this.length;
      for (var i = 0; i < l; i++) {
        c(this[i], i, this);
      }
    };
  Array.prototype.each2 = function (c) {
      var l = this.length;
      for (var i = 0; i < l; i++) {
        c(this[i], i);
      }
    };

Test runner

Ready to run.

Testing in
TestOps/sec
For..in loop
for (var i in arr) {
  someFn(arr[i]);
}
ready
forEach
arr.forEach(function(v) {
  someFn(v)
})
ready
While ! Undefined
i = 0;
while ((a = arr[i++]) !== undefined) {
  someFn(a);
}
ready
Order w/ array copy
arr2 = [];
while (i = arr.shift()) {
  someFn(i);
  arr2.push(i);
}
arr = arr2;
ready
shift()
arr2 = []
l = 0;
while (i = arr.shift()) {
  someFn(i);
  arr2[l] = i;
  l++;
}
arr = arr2;
ready
Forloop ! Null
for (var i = 0, item;
  (item = arr[i]) != null; i++) {
  someFn(item);
}
ready
Reverse For-loop
for (var i = arr.length; --i;) {
  someFn(arr[i]);
}
ready
Map
arr.map(someFn)
ready
custom each
arr.each(function(i) {
  someFn(i);
})
ready
custom each2
arr.each2(function(i) {
  someFn(i);
})
ready
1staslast
for (i = 0; i < arr.length; i++) {
  someFn(arr[i]);
}
ready
Do-while loop, --i
i = arr.length;
if (i > 0) {
  do {
    someFn(arr[i]);
  }
  while (--i);
}
ready
Do-while loop, i--
i = arr.length - 1;
do {
  someFn(arr[i]);
}
while (i--);
ready
For loop, i--
for (i = arr.length; i > 0; i--) {
  someFn(arr[i]);
}
ready
For loop, cached
for (i = 0, len = arr.length; i < len; i++) {
  someFn(arr[i]);
}
ready
While loop, basic
i = 0;
while (i != arr.length) {
  someFn(arr[i++]);
}
ready
For loop, basic
for (i = 0; i < arr.length; i++) {
  someFn(arr[i]);
}
ready

Revisions

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