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JavaScript String replaceAll

David Walsh
Published: December 27, 2021

Replacing a substring of text within a larger string has always been misleading in JavaScript. I wrote Replace All Occurrences of a String in JavaScript years ago and it’s still one of my most read articles.

The confusion lies in that replace only replaces the first occurrence of a substring, not all occurrences. For example:

'yayayayayaya'.replace('ya', 'na');
// nayayayayaya

To replace all instances of a substring, you’ve needed to use a regular expression:

'yayayayayaya'.replace(/ya/g, 'na');
// nananananana

Using regular expressions is certainly powerful but let’s be honest — oftentimes we simply want to replace all instances of a simple substring that shouldn’t require a regular expression.

Luckily, this year the JavaScript language provided us with String.prototype.replaceAll, a method for replacing without using regular expressions:

'yayayayayaya'.replaceAll('ya', 'na');
// nananananana

Sometimes an API exists in a confusing format and standards bodies simply need to improve the situation. I’m glad they did so with replaceAll!

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