用正则表达式替换匹配的第n个匹配项

Question

I'm trying to find a way to replace nth match of more matches lite this.

string = "one two three one one"

How do I target the second occurence of "one"?

Is it possible to do something like this?

string.replace(/\bone\b/gi{2}, "(one)")

to get something like this

"one two three (one) one"

I've done a jsfiddle which is working but it doesn't feel right. Heaps of code and confusing for a simple thing.

https://jsfiddle.net/Rickii/7u7pLqfd/

Answer 1

Update :

To make it dynamic use this:

((?:.*?one.*?){1}.*?)one

where the value 1 means (n-1); which in your case is n=2

and replace by:

$1\(one\)

Regex101 Demo

 const regex = /((?:.*?one.*?){1}.*?)one/m; const str = `one two three one one asdfasdf one asdfasdf sdf one`; const subst = `$1\\(one\\)`; const result = str.replace(regex, subst); console.log( result); 

Answer 2

A more general approach would be to use the replacer function.

 // Replace the n-th occurrence of "re" in "input" using "transform" function replaceNth(input, re, n, transform) { let count = 0; return input.replace( re, match => n(++count) ? transform(match) : match); } console.log(replaceNth( "one two three one one", /\\bone\\b/gi, count => count ===2, str => `(${str})` )); // Capitalize even-numbered words. console.log(replaceNth( "Now is the time", /\\w+/g, count => !(count % 2), str => str.toUpperCase()));