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How to Remove or Replace All Whitespace from a String in JavaScript

Removing or replacing whitespace is a fundamental string manipulation task, essential for data sanitization, formatting, and preparing strings for comparison. A common requirement is to remove all whitespace characters (including spaces, tabs, and newlines) or to replace them with a different character.

This guide will demonstrate the modern and most effective methods for this task using String.prototype.replace() with a regular expression and the newer String.prototype.replaceAll().

The Core Task: Removing All Whitespace vs. Only Spaces​

It's important to distinguish between two common goals:

  • Removing All Whitespace: This means removing every space, tab (\t), newline (\n), and any other whitespace character.
  • Removing Only Space Characters: This means removing only the standard space character ( ) while leaving tabs and newlines intact.

The best method depends on which of these you need to do.

Removing All Whitespace (Spaces, Tabs, Newlines)​

For this task, a regular expression is the most powerful and reliable tool.

Problem: you have a string with a mix of different whitespace characters that you want to remove completely.

// Problem: Remove all spaces, tabs, and newlines from this string.
const messyString = '  Hello\tWorld\n This is a test.  ';

Solution: use String.prototype.replace() with the /\s/g regular expression.

function removeAllWhitespace(str) {
  // The regex /\s/g finds all whitespace characters globally.
  return str.replace(/\s/g, '');
}

// Example Usage:
const messyString = '  Hello\tWorld\n This is a test.  ';
const cleanString = removeAllWhitespace(messyString);

console.log(cleanString); // Output: 'HelloWorldThisisatest.'
note

This is the recommended best practice for removing all types of whitespace.

Removing or Replacing Only Space Characters​

If your goal is to target only the standard space character, the modern String.prototype.replaceAll() method is the most readable and direct solution.

Problem: you want to replace all spaces with a different character (like a hyphen), but leave other whitespace like newlines alone.

// Problem: Replace only the spaces with hyphens.
const sentence = 'This is a sentence.\nAnd another line.';

Solution: use replaceAll() with a simple string argument.

const sentence = 'This is a sentence.\nAnd another line.';

// Replace every space character with a hyphen.
const hyphenated = sentence.replaceAll(' ', '-');

console.log(hyphenated);
// Output: 'This-is-a-sentence.\nAnd-another-line.'

// To remove the spaces instead, just replace with an empty string.
const noSpaces = sentence.replaceAll(' ', '');
console.log(noSpaces); // Output: 'Thisisasentence.\nAndanotherline.'
note

This is the recommended best practice when you only need to target the space character.

How the Regular Expression Works​

The regular expression /\s/g is the key to removing all whitespace.

  • / ... /: The delimiters that mark the beginning and end of the regular expression.
  • \s: A special "metacharacter" that matches any whitespace character. This includes the space, tab, newline, carriage return, and others.
  • g: This is the global flag. It is crucial. It tells the replace() method to replace all matches it finds, not just the first one.

So, /\s/g translates to: "Find every whitespace character, wherever it appears in the string." The replace() method then replaces these matches with an empty string, effectively deleting them.

Conclusion​

Removing or replacing whitespace is a simple task with clear, modern solutions in JavaScript.

  • To remove all types of whitespace (spaces, tabs, newlines, etc.), the recommended best practice is to use replace() with a global regular expression: str.replace(/\s/g, '').
  • To remove or replace only the space character, the most readable and modern method is str.replaceAll(' ', '').

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