Run results for: cost of eventListeners

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/112.0

Browser: Firefox 112

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
running async 1000 event listeners	5.3 Ops/sec
running async 501 event listeners	1.6 Ops/sec

Script Preparation code:

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

Tests:

running async 1000 event listeners
for (var i = 0; i <1000; i++) audio.addEventListener("ratechange",andAOne.bind({})); audio.playbackRate = 2;
running async 501 event listeners
for (var i = 0; i <1000; i++) audio.addEventListener("ratechange",andAOneAndAStop.bind({})); audio.playbackRate = 2;

Run results for: cost of eventListeners

meassuring the cost of just calling an event listener.

running async 1000 event listeners

running async 501 event listeners