Performance of Array vs. Object

JavaScript performance comparison

Revision 47 of this test case created

Info

After seeing http://jsperf.com/javascript-associative-vs-non-associative-arrays, I thought the test could be improved.

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var arr = [],
        i, obj = {};
    for (i = 0; i < 100000; i += 1) {
      var o = {
        payload: i
      };
      arr.push(o);
      obj[i] = o;
    }
   
    function jaakkoForEach(array, callback, scope) {
        var x, l = array.length, i = 0;
   
        scope = scope || this;
   
        while (i < l) {
            x = array[i];
            callback.call(scope, x, i);
            ++i;
        }
    }
};
</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 < 100000; ++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 forEach
var sum = 0;
arr.forEach(function(obj) {
  sum += obj.payload;
});
 
pending…
Cache length
var sum = 0;
var al = arr.length;
for (var x = 0; x < al; ++x) {
  sum += arr[x].payload
}
pending…
for..in for array
var sum = 0;
for (var x in arr) {
  sum += arr[x].payload;
}
pending…
while backwards
var i = arr.length;
var sum = 0;
while(--i) {
  sum += arr[i].payload
}
pending…
var sum = 0;
jaakkoForEach(arr, function(obj) {
  sum += obj.payload;
});
pending…
var sum = arr.reduce(function(memo, val) {
  return memo += val.payload;
},0);
pending…

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