array.length vs. cached

JavaScript performance comparison

Revision 20 of this test case created by

Preparation code


      
      <script>
Benchmark.prototype.setup = function() {
  var a = [];
  for (var i = 0; i < 100000; i++) {
    a.push(i);
  }

};
</script>

Test runner

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
not cached at all
(function(a) {
  var k = 0;
  for (var i = 0; i < a.length; i++) {
    k = a[i];
  }
  return k;
})(a);
pending…
var outside for i += 1
(function(a) {
  var k = 0,
      i = 0,
      aLen = a.length;
  for (; i < aLen; i += 1) {
    k = a[i];
  }
  return k;
})(a);
pending…
var outside for
(function(a) {
  var k = 0,
      i = 0,
      aLen = a.length;
  for (; i < aLen; i++) {
    k = a[i];
  }
  return k;
})(a);
pending…
for i += 1
(function(a) {
  var k = 0;
  for (var i = 0, aLen = a.length; i < aLen; i += 1) {
    k = a[i];
  }
  return k;
})(a);
pending…
for i++
(function(a) {
  var k = 0;
  for (var i = 0, aLen = a.length; i < aLen; i++) {
    k = a[i];
  }
  return k;
})(a);
pending…

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