Run results for: NodeList For vs Foreach

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:79.0) Gecko/20100101 Firefox/79.0

Browser: Firefox 79

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Default For	1580.5 Ops/sec
For with length caching	1750.6 Ops/sec
forEach	2903313.0 Ops/sec

Script Preparation code:

var div = document.createElement('div');
for (let i = 0; i < 1000; i++) {
    div.insertAdjacentHTML('beforeend', `<span>span-${i}<span>`);
}

var list = div.querySelectorAll('span');

Tests:

Default For
for(let i = 0; i < list.length; i++) { list[i].setAttribute('tabindex', '-1'); }
For with length caching
list.forEach(item =>{ item.setAttribute('tabindex', '-1'); });
forEach
for(let i = 0, lenght = list.lenght ; i < length; i++) { list[i].setAttribute('tabindex', '-1'); }

Run results for: NodeList For vs Foreach

Default For

For with length caching

forEach