Run results for: for in break vs object keys really better

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.77 Safari/537.36

Browser: Chrome 91

Operating system: Linux

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
for in break	896.8 Ops/sec
Object keys	322.3 Ops/sec
Object keys for real	809.5 Ops/sec

Script Preparation code:

var testObj = {}
for (let i = 0; i < 10000; i++) {
  const randomString = Math.random().toString(36).substr(2, 5);
  testObj[randomString] = randomString;
}

Tests:

for in break
let output; for (const key in testObj) { output = testObj[key]; break; } console.log(output);
Object keys
let output; output = Object.values(testObj)[0]; console.log(output);
Object keys for real
let output; output = testObj[Object.keys(testObj)[0]]; console.log(output);

Run results for: for in break vs object keys really better

for in break

Object keys

Object keys for real