Run results for: EventListener cost

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:79.0) Gecko/20100101 Firefox/79.0

Browser: Firefox 79

Operating system: Linux

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
async 1000	10.3 Ops/sec
async 501	4.0 Ops/sec
sync 1000	24.7 Ops/sec
sync 501	8.4 Ops/sec
sync 1000 with a fake stopImmediatePropagation()	6.3 Ops/sec
async 1000 with a fake stopImmediatePropagation()	3.7 Ops/sec

Script Preparation code:

var audio = document.createElement("audio");

function andAOne(e){ 
  e.count = (e.count|| 0) +1; 
  e.count === 501 && e.preventDefault();
}

function andAOneAndAStop(e){ 
  e.count = (e.count|| 0) +1; 
  e.count === 501 && e.stopPropagationImmediately();
}

function andAOneAndANeverStop(e){ 
  e.count = (e.count|| 0) +1; 
  e.count === 5001 && e.stopPropagationImmediately();
}

Tests:

async 1000
for (var i = 0; i <100; i++) audio.addEventListener("ratechange",andAOne.bind({})); audio.playbackRate = 2;
async 501
for (var i = 0; i <100; i++) audio.addEventListener("ratechange",andAOneAndAStop.bind({})); audio.playbackRate = 2;
sync 1000
for (var i = 0; i <100; i++) audio.addEventListener("click",andAOne.bind({})); audio.click();
sync 501
for (var i = 0; i <100; i++) audio.addEventListener("click",andAOneAndAStop.bind({})); audio.click();
sync 1000 with a fake stopImmediatePropagation()
for (var i = 0; i <100; i++) audio.addEventListener("click",andAOneAndANeverStop.bind({})); audio.click();
async 1000 with a fake stopImmediatePropagation()
for (var i = 0; i <100; i++) audio.addEventListener("ratechange",andAOneAndANeverStop.bind({})); audio.playbackRate = 2;

Run results for: EventListener cost

what are the costs of running different event listeners?

async 1000

async 501

sync 1000

sync 501

sync 1000 with a fake stopImmediatePropagation()

async 1000 with a fake stopImmediatePropagation()