Performance of Array vs. Object

JavaScript performance comparison

Revision 36 of this test case created by imma

Info

I wanted to try out a new test

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var arr = [],
      i,
      obj = {};
    for (i = 0; i < 10000; i += 1) {
      var o = {
        payload: i
      };
      arr.push(o);
      obj[i] = o;
    }
};
</script>

Test runner

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Testing in unknown unknown
Test Ops/sec
Array Performance
var sum = 0;
for (var x = 0; x < arr.length; ++x) {
  sum += arr[x].payload
}
pending…
Object Performance
var sum = 0;
for (var x in obj) {
  sum += obj[x].payload;
}
pending…
Object Performance using known length
var sum = 0;
for (var x = 0; x < 10000; ++x) {
  sum += obj[x].payload
}
pending…
Using Object.keys()
var sum = 0;
var keys = Object.keys(obj);
for (var x = 0; x < keys.length; ++x) {
  sum += obj[keys[x]].payload
}
pending…
Using obj[length] === undefined (== false)
var sum = 0,
  x = 0,
  o;
for (; o = obj[x++];) {
  sum += o.payload
}
pending…
Reverse array looping
var sum = 0;
for (var x = arr.length; x--;) {
  sum += arr[x].payload
}
pending…
Reduce
var sum = arr.reduce(function(carry, item) {
  return carry + item.payload
});
pending…
Array pre-length
var sum = 0;
for (var x = 0, l = arr.length; x < l; ++x) {
  sum += arr[x].payload
}
pending…
Array pre-length alt inc
var sum = 0;
for (var x = 0, l = arr.length; x < l; x++) {
  sum += arr[x].payload
}
pending…
Double check original
var sum = 0;
for (var x = 0; x < arr.length; ++x) {
  sum += arr[x].payload
}
pending…

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