typeof vs undefined check

JavaScript performance comparison

Revision 2 of this test case created by LJHarb

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var x = undefined,
        y = true;
};
</script>

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Testing in unknown unknown
Test Ops/sec
typeof x === "undefined"
typeof x === "undefined";
typeof y === "undefined";
pending…
x===undefined
x === undefined;
y === undefined;
pending…

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