Run results for: event delegation vs local handlers

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0 Waterfox/56.3

Browser: Firefox 56

Operating system: Windows 7

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
one	554699.6 Ops/sec
manyDel	514639.4 Ops/sec
manyLoc	282070.2 Ops/sec

HTML Preparation code:

<ul class='one'>
</ul>

<ul class='manyDel'>
</ul>

<ul class='manyLoc'>
</ul>

<template class='content'>
  <li><a class='link' data-x='2'></a></li>
</template>

Script Preparation code:

var templ = document.querySelector(`.content`);

var one = document.querySelector(`.one`);
one.append(templ.cloneNode(true).content);
var oneLink = one.querySelector(`.link`);

var manyDel = document.querySelector(`.manyDel`);
var manyDelLinks = [];

var manyLoc = document.querySelector(`.manyLoc`);
var manyLocLinks = [];

var x = 0;
function handleEvent(ev) {
  x += (ev.target.dataset.x|0);
}

var n = 1000;
for (let i = 0; i < n; ++i) {
  let frag = templ.cloneNode(true).content;
  manyDelLinks.push(frag.querySelector(`.link`));
  manyDel.append(frag);
  
  frag = templ.cloneNode(true).content;
  frag.querySelector(`.link`).addEventListener(`test`, handleEvent);
  manyLocLinks.push(frag.querySelector(`.link`));
  manyLoc.append(frag);
}

one.addEventListener(`test`, handleEvent);
manyDel.addEventListener(`test`, handleEvent);

Tests:

one
oneLink.dispatchEvent(new CustomEvent(`test`, {bubbles : true}));
manyDel
manyDelLinks[(Math.random() * n)|0].dispatchEvent(new CustomEvent(`test`, {bubbles : true}));
manyLoc
manyLocLinks[(Math.random() * n)|0].dispatchEvent(new CustomEvent(`test`, {bubbles : true}));