Run results for: Bound Symbol.iterator effect on for..of loop performance

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36

Browser: Chrome 92

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
native set	39972.5 Ops/sec
set with [Symbol.iterator] modified to a bound function	54972.0 Ops/sec

Script Preparation code:

var randomArray = [];
for (let i = 0; i < 10000; i++) {
  randomArray[i] = i*i;
}

var set1 = new Set(randomArray);
var set2 = new Set(randomArray);
set2[Symbol.iterator] = set2[Symbol.iterator].bind(set2);

Tests:

native set
for (let item of set1) { if (typeof item !== 'number') { throw new Error('wtf'); } }
set with [Symbol.iterator] modified to a bound function
for (let item of set2) { if (typeof item !== 'number') { throw new Error('wtf'); } }

Run results for: Bound Symbol.iterator effect on for..of loop performance

It is believed that v8 optimizes for..of loops in some way. Will this optimization goes away if [Symbol.iterator] is replaced to a bound function?

native set

set with [Symbol.iterator] modified to a bound function