in vs == undefined

JavaScript performance comparison

Test case created by Michiel Dral

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var object = {};
};
</script>

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Testing in unknown unknown
Test Ops/sec
in
if('key' in object) {};
pending…
== undefined
if(typeof object.key == 'undefined') {};
pending…

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