JavaScript · Regular expressions

replace with function

A replacement function receives the match and captures, which makes conditional rewrites easy.

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Syntax

text.replace(re, (match, …groups) => value)

Example

Try it

console.log("a1b2".replace(/([a-z])(\d)/g, (_, letter, digit) => digit + letter));

Reference pages are the quick answer. The course explains the why, shows the full example and ends with a challenge.