Replace special characters in a string with _ (underscore)

Question

I want to remove special characters from a string and replace them with the _ character.

For example:

string = "img_realtime_tr~ading3$"

The resulting string should look like "img_realtime_tr_ading3_";

I need to replace those characters: & / \ # , + ( ) $ ~ % .. ' " : * ? < > { }

why is this closed, it's a good question. How to replace special characters, useful when making SE-friendly URL's. Thankfully still someone replied to it. — bicycle, Jan 27 '13 at 14:16
An extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet ? Well let's just say that at least 108 persons where thinking otherwise. — Antoine Pelletier, Feb 13 '17 at 18:19

score 271 · Answer 1 · edited Dec 19 '19 at 12:49

271

string = string.replace(/[&\/\\#,+()$~%.'":*?<>{}]/g,'_');

Alternatively, to change all characters except numbers and letters, try:

string = string.replace(/[^a-zA-Z0-9]/g,'_');

edited Dec 19 '19 at 12:49

Jacob Tomlinson

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answered Mar 14 '12 at 15:46

Niet the Dark Absol

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Cool! `!` is missing in the first line though. – ProblemsOfSumit Dec 11 '14 at 17:11
7

Second line is very useful in a number of occasions. – mastazi Jun 15 '15 at 10:54
``\-`` and ``=`` also missing :) – Simo Mafuxwana Jan 12 '16 at 12:59
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If you have a special character before a space like `hello! word` you will end up with two underscore consecutive like this `hello__word` so, you can do this: `string = string.replace(/[^a-zA-Z0-9]/g,'_').replace(/__/g,'_');` – DannyFeliz Dec 12 '16 at 03:07
6

@DannyFeliz or even `string = string.replace(/[^a-zA-Z0-9]/g,'_').replace(/_{2,}/g,'_');` if you do not know how many consecutive underscores – falkodev Mar 16 '17 at 12:16
what does g mean?? – Anil Kumar Reddy Oct 12 '17 at 08:56
@AnilKumarReddy the g modifier is used to perform a global match (find all matches rather than stopping after the first match). – Pol Fernández Jan 19 '18 at 12:45
The second variant will drop French or other languages characters – Ihor Nov 16 '21 at 16:04

score 10 · Answer 2 · answered Jun 12 '20 at 06:10

10

string = string.replace(/[\W_]/g, "_");

answered Jun 12 '20 at 06:10

Wen

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score 0 · Answer 3 · answered Jul 04 '23 at 14:32

let myStr = "img_realtime_tr~ading3$ #Amoos !"

const replaceAccentsChars = (str, charWith='-', regexType='NO_SPECIAL' ) => {
  
    if(!str) return
  
    const REGEX_TYPE = {
      'ALL': / /g,
      'NO_SPECIAL': /[^A-Z0-9]/ig,
      'SINGLE_FOR_MULTI': /[^A-Z0-9]+/ig,
    }

    return str.replace(REGEX_TYPE[regexType], charWith).toLowerCase()
}


console.log(
  replaceAccentsChars(myStr)
)

// Speical Chars Allowed & String as params
console.log(
  replaceAccentsChars(myStr, '*', 'ALL')
)

console.log(
  replaceAccentsChars(myStr, '_', 'SINGLE_FOR_MULTI')
)

Replace special characters in a string with _ (underscore)

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