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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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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=536859" width="100%" height="500px"></iframe>
Run details:
User agent:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.5 Safari/605.1.15
Browser:
Safari 17
Operating system:
Mac OS X 10.15.7
Device Platform:
Desktop
Date tested:
2 years ago
Benchmark engine:
Benchmark.js
typeof string is undefined
607.2M/s
typeof undefined is undefined
20.4M/s
string is undefined
20.0M/s
undefined is undefined
10.5M/s
View exact numbers
Test name
Executions per second
✓
typeof string is undefined
607,229,952 Ops/sec
typeof undefined is undefined
20,353,254 Ops/sec
string is undefined
20,009,026 Ops/sec
undefined is undefined
10,495,912 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