Run results for: querySelector vs querySelector + cache

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:122.0) Gecko/20100101 Firefox/122.0

Browser: Firefox 122

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

querySelector

1.3M/s

querySelector + cache

41K/s

View exact numbers

Test name	Executions per second
✓ querySelector	1,259,401 Ops/sec
querySelector + cache	40,843 Ops/sec

HTML Preparation code:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1 class="about-shop">Hello azula</h1>
</body>
</html>

Script Preparation code:

const cache = {};

    function $(selector) {
        if (cache[selector] !== undefined) {
            console.count("cached");
            return cache[selector];
        }

        const cached = document.querySelector(selector);
        cache[selector] = cached;
        return cached
    };

Tests:

querySelector
const selector1 = document.querySelector(".about-shop"); const selector2 = document.querySelector(".about-shop"); const selector3 = document.querySelector(".about-shop");
querySelector + cache
const selector1 = $(".about-shop"); const selector2 = $(".about-shop"); const selector3 = $(".about-shop");