To replace all numbers in a string, call the `replace()` method, passing it a regular expression that globally matches all numbers as the first parameter and the replacement string as the second.

Replace all Numbers in a String using JavaScript


## Replace all Numbers in a String

**To replace all numbers in a string, call the `replace()` method, passing it a
regular expression that globally matches all numbers as the first parameter and
the replacement string as the second.**

The `replace` method will return a new string with all matches replaced by the
provided replacement.

```javascript:index.js
const str = 'a1 b2 c3';

const replaced = str.replace(/[0-9]/g, '!');
console.log(replaced); // 👉️ a! b! c!
```

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We pass the following parameters to the
[String.replace](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace)
method:

1. a regular expression we want to match in the string. In our case we want to
   match all numbers from 0-9
2. a replacement string for each match

**The brackets `[]` part of a regular expression is called a character class. In
our character class we match all numbers in the range from 0-9.**

We use the `g` (global) flag, because we want to match all occurrences of a
number in the string and not just the first occurrence.

If you need help reading a regular expression, check out this
[regex cheatsheet](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Cheatsheet)
from MDN. It's definitely the best one out there.

<Alert>
  The <code>replace</code> method does not change the original string, it
  returns a new string with one or more matches replaced. Strings are immutable
  in JavaScript.
</Alert>

The example uses an exclamation mark as the replacement, however you could use
whatever replacement string suits your use case, e.g. an underscore.

```javascript:index.js
const str = 'a1 b2 c3';

const replaced = str.replace(/[0-9]/g, '_');
console.log(replaced); // 👉️ a_ b_ c_
```

An equivalent regular expression, is to use the `\d` special character.

```javascript:index.js
const str = 'a1 b2 c3';

const replaced = str.replace(/\d/g, '!');
console.log(replaced); // 👉️ a! b! c!
```

The `\d` special character matches any digit 0-9. It achieves the same goal as
`[0-9]`.

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Replace all Numbers in a String using JavaScript

Replace all Numbers in a String #

Borislav Hadzhiev

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Replace all Numbers in a String using JavaScript