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Run results for:
is variable undefined? typeof variable === "undefined" vs variable === undefined
Comparing whether checking is (typeof variable === "undefined") is faster than (variable === undefined)
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<iframe src="https://measurethat.net/Embed?id=497412" width="100%" height="500px"></iframe>
Run details:
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:121.0) Gecko/20100101 Firefox/121.0
Browser:
Firefox 121
Operating system:
Windows
Device Platform:
Desktop
Date tested:
2 years ago
Test name
Executions per second
typeof string is undefined
697428992.0 Ops/sec
typeof undefined is undefined
697516096.0 Ops/sec
string is undefined
687491008.0 Ops/sec
undefined is undefined
696407168.0 Ops/sec
Tests:
typeof string is undefined
typeof "not undefined" === "undefined"
typeof undefined is undefined
typeof undefined === "undefined"
string is undefined
"not undefined" === undefined
undefined is undefined
undefined === undefined