Javascript: Regex to escape parentheses and spaces

Question

Looking to backslash escape parentheses and spaces in a javascript string.

I have a string: (some string), and I need it to be $some\ string$

Right now, I'm doing it like this:

x = '(some string)'
x.replace('(','\\(')
x.replace(')','\\)')
x.replace(' ','\\ ')

That works, but it's ugly. Is there a cleaner way to go about it?

Your code doesn't actually work. It will only replace the first occurrence of each character, not all of them. — Barmar, Apr 04 '14 at 21:09

score 14 · Accepted Answer · answered Apr 04 '14 at 21:04

14

you can do this:

x.replace(/(?=[() ])/g, '\\');

(?=...) is a lookahead assertion and means 'followed by'

[() ] is a character class.

answered Apr 04 '14 at 21:04

What's the point of the lookahead here? Why not just match `/[() ]/g`? – talemyn Apr 04 '14 at 21:12
Ah, nevermind . . . I missed that you weren't using the capturing group in the replacement string. – talemyn Apr 04 '14 at 21:13
1

@talemyn: Yes, it is for this reason. However a solution as Barmar wrote works well too. – Casimir et Hippolyte Apr 04 '14 at 21:16
This worked - though now there is a new wrinkle. I need to add the dash `-` to the list of escaped characters, though that seems to eliminate everything which follows the dash from the string. – Kevin Whitaker Apr 04 '14 at 21:31
@KevinWhitaker: the dash is a special character in a character class (it is used to define character ranges), you can: 1) escape it, 2) put it at the begining of the character class, 3) put it at the end of the character class. – Casimir et Hippolyte Apr 04 '14 at 21:46
Thanks Casimir! That did it! – Kevin Whitaker Apr 04 '14 at 21:48

score 3 · Answer 2 · answered Apr 04 '14 at 21:08

3

Use a regular expression, and $0 in the replacement string to substitute what was matched in the original:

x = x.replace(/[() ]/g, '\\$0')

answered Apr 04 '14 at 21:08

Barmar

2 Answers2