Benchmark: key in object vs. object[key] === undefined

Script Preparation code:

var obj = {a: 5, b: 8};

Tests:

Using in keyword
"a" in obj; "b" in obj; "c" in obj;
Using === undefined
obj["a"] === undefined; obj["b"] === undefined; obj["c"] === undefined;

Rendered benchmark preparation results:

Previous results

Test case name	Result
Using in keyword
Using === undefined

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Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Mac OS X 10.15.7

Test name	Executions per second
Using in keyword	10786470.0 Ops/sec
Using === undefined	3979698.0 Ops/sec

key in object vs. object[key] === undefined (version: 0)