[javascript] How to remove numbers from a string?

I want to remove numbers from a string:

questionText = "1 ding ?"

I want to replace the number 1 number and the question mark ?. It can be any number. I tried the following non-working code.

questionText.replace(/[0-9]/g, '');

Just want to add since it might be of interest to someone, that you may think about the problem the other way as well. I am not sure if that is of interest here, but I find it relevant.

What I mean by the other way is to say "strip anything that aren't what I am looking for, i.e. if you only want the 'ding' you could say:

var strippedText = ("1 ding ?").replace(/[^a-zA-Z]/g, '');

Which basically mean "remove anything which is nog a,b,c,d....Z (any letter).

You can use .match && join() methods. .match() returns an array and .join() makes a string

function digitsBeGone(str){
  return str.match(/\D/g).join('')
}

A secondary option would be to match and return non-digits with some expression similar to,

/\D+/g

which would likely work for that specific string in the question (1 ding ?).

Demo

Test

function non_digit_string(str) {_x000D_
 const regex = /\D+/g;_x000D_
 let m;_x000D_
_x000D_
 non_digit_arr = [];_x000D_
 while ((m = regex.exec(str)) !== null) {_x000D_
  // This is necessary to avoid infinite loops with zero-width matches_x000D_
  if (m.index === regex.lastIndex) {_x000D_
   regex.lastIndex++;_x000D_
  }_x000D_
_x000D_
_x000D_
  m.forEach((match, groupIndex) => {_x000D_
   if (match.trim() != '') {_x000D_
    non_digit_arr.push(match.trim());_x000D_
   }_x000D_
  });_x000D_
 }_x000D_
 return non_digit_arr;_x000D_
}_x000D_
_x000D_
const str = `1 ding ? 124_x000D_
12 ding ?_x000D_
123 ding ? 123`;_x000D_
console.log(non_digit_string(str));

If you wish to simplify/modify/explore the expression, it's been explained on the top right panel of regex101.com. If you'd like, you can also watch in this link, how it would match against some sample inputs.

RegEx Circuit

jex.im visualizes regular expressions:

You're remarkably close.

Here's the code you wrote in the question:

questionText.replace(/[0-9]/g, '');

The code you've written does indeed look at the questionText variable, and produce output which is the original string, but with the digits replaced with empty string.

However, it doesn't assign it automatically back to the original variable. You need to specify what to assign it to:

questionText = questionText.replace(/[0-9]/g, '');

String are immutable, that's why questionText.replace(/[0-9]/g, ''); on it's own does work, but it doesn't change the questionText-string. You'll have to assign the result of the replacement to another String-variable or to questionText itself again.

var cleanedQuestionText = questionText.replace(/[0-9]/g, '');

or in 1 go (using \d+, see Kobi's answer):

 questionText = ("1 ding ?").replace(/\d+/g,'');

and if you want to trim the leading (and trailing) space(s) while you're at it:

 questionText = ("1 ding ?").replace(/\d+|^\s+|\s+$/g,'');

This can be done without regex which is more efficient:

var questionText = "1 ding ?"
var index = 0;
var num = "";
do
{
    num += questionText[index];
} while (questionText[++index] >= "0" && questionText[index] <= "9");
questionText = questionText.substring(num.length);

And as a bonus, it also stores the number, which may be useful to some people.