Today I Learned - Rocky Kev

TIL what matters for JS optimization

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TAGS: javascript loops memory

Two years ago, I remember arguing with a coworker over what loops to use for optimization. (Spoiler: congrats on saving milliseconds on something that might be optimized a few months later)

Via Writing high-performance JavaScript

When writing High Performance Javascript, here's doesn't matter for Javascript Optimization:

Doesn't matter:

Using getElementById() vs querySelector():

For example, you may read that document.getElementById() is more than twice as fast as document.querySelector(), and start fretting about which selector method to use when.

It’s true, by the way. The document.getElementById() method can run about 15 million operations a second, compared to “just” 7 million per second for the document.querySelector() method in the latest version of Chrome. But that also means that the document.querySelector() method runs 7,000 operations a millisecond. That’s really damn fast!

Loops:

I also similarly see people worry about things like which loop method is faster.

Here's a blog post with data: https://blog.bitsrc.io/measuring-performance-of-different-javascript-loop-types-c0e9b1d193ed

And similar to the above comment... imagine shaving fractions of fractions of fractions of seconds off.

There's way better optimization you can look at.

Matters

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