Performance of Array vs. Object

JavaScript performance comparison

Revision 43 of this test case created by Dirk

Info

Added tests using Underscore.js

Preparation code

<script src="//cdnjs.cloudflare.com/ajax/libs/underscore.js/1.5.2/underscore-min.js"></script>
<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>

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Testing in unknown unknown
Test Ops/sec
Array Performance
var sum = 0;
for (var x=0, len = arr.length; x<len; ++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, len = keys.length;x<len; ++x) {
    sum += obj[keys[x]].payload
}
pending…
Array in
var sum = 0;
for (var x in arr) {
    sum += x.payload
}
pending…
Array using Underscore.js
var sum = 0;
_.each(arr, function(x) {
    sum += x.payload
});
pending…
Object using Underscore.js
var sum = 0;
_.each(obj, function(x) {
    sum += x.payload
});
pending…

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