JavaScript Regex is Slow

Regular Expression or oftenly regex is a pattern that used for matching. But one thing you should know, regex in JavaScript is kinda slow on SIMPLE pattern usage. If your pattern is simple, i RECOMMEND to DON’T use regex.

For example, this regex usage:

const pola = /^Hi/;
console.log(pola.test("Hi world"));

Can be replaced with:

console.log("Hi world".startsWith("Hi"));

You can check an example from my JavaScript library fast-camelcase-css. It isn’t using regex, but using manual operation from some methods on String.prototype and while loop. And the result can be 3-8 times faster than regex usage.

But if your pattern is kinda complex, i recommend to still use regex than manual operation. Why? Because manual operation on complex case can be slower than regex operation.