CODEWITHSUNDEEP
javascriptregex
qn0361
qn0361

Reputation: 47

Remove consecutive characters of certain type with RegExp in JS

I need a regex for removing specific consecutive characters.

For example. I can use 

var filtered = oldString.replace(/[^[\w]\s]|(.)(?=\1)/gi, "");

If I need to get rid of any consecutive characters.

And I can use.

var filtered = oldString.replace(/[^[\w]\s]|(,|;|\s)(?=\1)/gi, "");

If I need to get rid of consecutive commas, semi-colons and space characters.

But what I exactly need is to make string like ;, look like ;.

And string like ,,,,, ; look like single comma ,.

So I need to get rid of any consecutive chars of some type.

How I am supposed to do that?

Upvotes: 2

Views: 648

Answers (2)

degant
degant

Reputation: 4981

Based on your question, my understanding is that you want to replace a set of predefined characters occurring consecutively with the first occurring one. You can do this:

([;,])[;,]*(?:[;,\h]*[;,]+)?
  • Matches any of ,, ; and horizontal spaces \h i.e single space or tab
  • Matches only spaces that occur in between
  • Using capturing group to capture first match i.e ([;,])
  • (?:[;,\h]*[;,]+)? is a non-capturing group which allows spaces in between

Replace with $1

This will replace a combination of ,, ; and spaces \h with the first one i.e

  • ,,,,,,,,; will get changed to ,
  • ;;;;; , , , , ;, ;, ; will get changed to ;

Regex101 Demo

Upvotes: 0

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626747

It seems you want to match chunks of the characters that are matched with the same pattern but keep the first matched char only. Use

.replace(/(\W)\W*/g, '$1')

See the regex demo

The pattern will match:

  • (\W) - a non-word char (and capture into Group 1 so that the $1 backreference in the replacement pattern could restore this char)
  • \W* - 0+ non-word chars (they will be removed from the string)

Note that this is a generic approach, and in most cases the pattern should be further adjusted.

Upvotes: 1

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