Fastest array loops in Javascript (v84)

Revision 84 of this benchmark created by Phillip Couto on

Setup

// Populate the base array
    var arr = [],
      newArr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = {
        a: 1,
        b: 1 + 'a'
      };
    }
  
    function someFn(obj) {
      return obj.a + 1;
    }

Test runner

Ready to run.

Testing in
TestOps/sec
For loop, basic
for (var i = 0; i < arr.length; i++) {
  someFn(arr[i]);
}
ready
While loop, basic
var i = 0;
while (i < arr.length) {
  someFn(arr[i]);
  i++;
}
ready
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
  someFn(arr[i]);
}
ready
For loop, i--
for (var i = arr.length - 1; i >= 0; i--) {
  someFn(arr[i]);
}
ready
Do-while loop, i--
var i = arr.length - 1;
do {
  someFn(arr[i]);
}
while (i--);
ready
Do-while loop, --i
var i = arr.length - 1;
if (i >= 0) {
  do {
    someFn(arr[i]);
  }
  while (--i);
}
ready
For..in loop
for (var i in arr) {
  someFn(arr[i]);
}
ready
Order
while (i = arr.shift()) {
  someFn(i);
  newArr.push(i);
}
ready
forEach
arr.forEach(function(v) {
  someFn(v)
})
ready
order validation
while ((i = arr.shift()) !== undefined) {
  someFn(i);
  newArr.push(i);
}
ready
While ! Undefined
var a;
while ((a = arr[i++]) !== undefined) {
  someFn(a);
}
ready
Pop
while (i = arr.pop()) {
  someFn(i);
  newArr.push(i);
}
ready
Order w/ array copy
var copy = arr.slice(0);
while (i = copy.shift()) {
  someFn(i);
}
ready
Pop w/ reverse()
arr.reverse();
while (i = arr.pop()) {
  someFn(i);
  newArr.push(i);
}
ready

Revisions

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