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.

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const str = 'a1 b2 c3';

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

We pass the following parameters to the 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 from MDN. It's definitely the best one out there.

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

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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.

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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].

Further Reading #

• Check if String contains any Letter in JavaScript
• Check if String contains Special Characters in JavaScript
• Check if String starts with Substring in JavaScript
• Check if String ends with Substring in JavaScript
• Check if String starts with one of Multiple Values in JS
• How to count the words in a String in JavaScript
• Check if String contains only Latin Letters in JavaScript
• Check if a String is all Uppercase in JavaScript
• Check if First Letter of String is Uppercase in JavaScript
• Get first letter of each Word in a String in JavaScript
• Remove the Last Word from a String using JavaScript