How to replace the number occurring before a pattern using regex in javascript?

Question

String: 56abc67xyz, 56abc67xyz68xyz, 12abc69xyzA

Output: 56abcxyz, 56abc67xyzxyz, 12abc69xyzA

So, the numbers occurring right before xyz should be removed but there shouldn't be anything after the xyz. It should be the last thing in the string.

CODE:

mystring.replace(/\d+xyz$/, '')

This code will remove the last xyz but I want to keep it as in example above.

Richard Henage · Accepted Answer · 2022-09-11 20:42:31Z

3

Use a Positive Lookahead: (?=). So if you want to check if something is there, but not match it, put it after the =, like this: \d+(?=xyz$)

console.log('56abc67xyz'.replace(/\d+(?=xyz$)/, ''))
console.log('56abc67xyz68xyz'.replace(/\d+(?=xyz$)/, ''))
console.log('12abc69xyzA'.replace(/\d+(?=xyz$)/, ''))

answered Sep 11, 2022 at 20:42

Richard Henage

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8 Comments

IT goldman Over a year ago

I would use \b instead of $ to capture a word boundary.

Laaouatni Anas Over a year ago

@richard good job upvoted, but I want to suggest also some little fixes if I can. 1) in the second use /g and not $. and it will be something like this /\d+(?=xyz)/g . g means global so it will check for multiple times (from left to right)

aste123 Over a year ago

@LaaouatniAnas Why do we need to check multiple times from left to right? There is only one occurrence and it occurs at the end of the string. Please let me know if I'm missing something.

aste123 Over a year ago

@ITgoldman what is the advantage of using \b over $ in this case?

IT goldman Over a year ago

just to match a few repetition of strings inside bigger text

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