in operator vs hasOwnProperty vs undefined value for key

JavaScript performance comparison

Test case created by Ash Heskes

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var testObj = {};
    var test_key = 9999;
   
    for ( var i = 0; i < 10000; i++ ){ testObj [ i ] = 1; };
};
</script>

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Testing in unknown unknown
Test Ops/sec
in operator
( test_key in testObj )
pending…
hasOwnProperty
( testObj.hasOwnProperty(test_key) )
pending…
undefined value
( testObj [ test_key ] === undefined )
pending…

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