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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=566706" width="100%" height="500px"></iframe>
Run details:
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36
Browser:
Chrome 131
Operating system:
Windows
Device Platform:
Desktop
Date tested:
one year ago
Test name
Executions per second
typeof string is undefined
97973232.0 Ops/sec
typeof undefined is undefined
7113451.5 Ops/sec
string is undefined
7272047.5 Ops/sec
undefined is undefined
3821498.5 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