Javascript replace with reference to matched group?

Question

I have a string, such as hello _there_. I'd like to replace the two underscores with <div> and </div> respectively, using JavaScript. The output would (therefore) look like hello <div>there</div>. The string might contain multiple pairs of underscores.

What I am looking for is a way to either run a function on each match, the way Ruby does it:

"hello _there_".gsub(/_.*?_/) { |m| "<div>" + m[1..-2] + "</div>" }

Or be able to reference a matched group, again the way it can be done in ruby:

"hello _there_".gsub(/_(.*?)_/, "<div>\\1</div>")

Any ideas or suggestions?

macabeus · Accepted Answer · 2022-04-18 22:29:16Z

534

"hello _there_".replace(/_(.*?)_/, function(a, b){
    return '<div>' + b + '</div>';
})

Oh, or you could also:

"hello _there_".replace(/_(.*?)_/, "<div>$1</div>")

edited Apr 18, 2022 at 22:29

macabeus

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answered Aug 5, 2009 at 17:51

airportyh

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6 Comments

daveloyall Over a year ago

Does Javascript use $1 instead of \1? Would someone provide a link to documentation?

daveloyall Over a year ago

replacementValue can be a function and it is passed different arguments based on the catch groups? Amazing!

jsh Over a year ago

i found \1 worked but $1 did NOT although I am using the RegExp variation: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

Stewart Over a year ago

@CalculatorFeline Saying "the regex itself" doesn't identify which one, as someone might be trying to use a regex for the replace. There must be many people trying to do this: "hello _there_".replace(/_(.*?)_/, /<div>\1<\/div>/).

Naramsim Over a year ago

Documentation about function replace developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

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Eifion · Accepted Answer · 2009-08-05 17:52:26Z

52

You can use replace instead of gsub.

"hello _there_".replace(/_(.*?)_/g, "<div>\$1</div>")

answered Aug 5, 2009 at 17:52

Eifion

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1 Comment

CalculatorFeline Over a year ago

You can remove the backslash.

Mohamed Allal · Accepted Answer · 2019-02-02 13:05:14Z

31

For the replacement string and the replacement pattern as specified by $. here a resume:

link to doc : here

"hello _there_".replace(/_(.*?)_/g, "<div>$1</div>")

Note:

If you want to have a $ in the replacement string use $$. Same as with vscode snippet system.

answered Feb 2, 2019 at 13:05

Mohamed Allal

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