Run results for: getBoundingClientRect

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 26_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Brave/1 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 26

Operating system: iOS 26.3.1

Device Platform: Mobile

Date tested: one month ago

Test name	Executions per second
getBoundingClientRect 10K	74.7 Ops/sec
elementFromPoint 10K	74.0 Ops/sec

HTML Preparation code:

<style>
    #container {
      width: 1000px;
      height: 1000px;
    }
    #container * {
      display: flex;
      flex: 1 1;
      background: red;
      border: 1px solid black;
      min-width: 0;
      min-height: 0;
      width: 100%;
      height: 100%;
    }
    #container .tick {
      flex-direction: row;
    }
    #container .tock {
      flex-direction: column;
    }
</style>
<div id="container"></div>

Script Preparation code:

const container = document.getElementById("container");
const depth = 12;
const childrenPerLevel = 3;

/**
 * @param {HTMLElement} parent
 * @param {boolean} isTick
 */
const addElement = (parent, isTick) => {
  const el = document.createElement("div");
  el.classList.add(isTick ? "tick" : "tock");
  parent.appendChild(el);
  return el;
};

let currLevel = [container];
let nextLevel = [];
for (let i = 0; i < depth; i++) {
  for (const parent of currLevel) {
    for (let j = 0; j < childrenPerLevel; j++) {
      nextLevel.push(addElement(parent, i % 2 === 0));
    }
  }
  currLevel = nextLevel;
  nextLevel = [];
}

Tests:

getBoundingClientRect 10K
const n = 10_000; const nsq = Math.floor(Math.sqrt(n)); const arr = Array(n).fill(0).map((v,i)=>i); arr.map((v,i)=>document.elementFromPoint(i%nsq, Math.floor(i/nsq))?.getBoundingClientRect);
elementFromPoint 10K
const n = 10_000; const nsq = Math.floor(Math.sqrt(n)); const arr = Array(n).fill(0).map((v,i)=>i); arr.map((v,i)=>document.elementFromPoint(i%nsq, Math.floor(i/nsq)));

Run results for: getBoundingClientRect

getBoundingClientRect 10K

elementFromPoint 10K