JavaScript Tutorials

JavaScript String replaceAll()
Syntax & Examples

String.replaceAll() method

The replaceAll() method of the String class in JavaScript is used to replace all occurrences of a specified pattern with a replacement string or the result of a function.

Syntax of String.replaceAll()

The syntax of String.replaceAll() method is:

replaceAll(pattern, replacement)

This replaceAll() method of String used to replace all occurrences of searchFor using replaceWith. searchFor may be a string or Regular Expression, and replaceWith may be a string or function.

Parameters

ParameterOptional/RequiredDescription
patternrequiredThe pattern to search for. It may be a string or a regular expression.
replacementrequiredThe replacement string or function to use when replacing occurrences of the pattern.

Return Type

String.replaceAll() returns value of type String.


✐ Examples

1 Using replaceAll() method to replace all occurrences of a substring

In JavaScript, the replaceAll() method can be used to replace all occurrences of a substring with another string.

For example,

  1. We define a string variable str with the value 'hello hello hello'.
  2. We use the replaceAll() method to replace all occurrences of 'hello' with 'world'.
  3. The result is stored in the variable newStr.
  4. We log newStr to the console using the console.log() method.

JavaScript Program

const str = 'hello hello hello';
const newStr = str.replaceAll('hello', 'world');
console.log(newStr);

Output

world world world

2 Using replaceAll() method with a regular expression

In JavaScript, the replaceAll() method can use a regular expression as the pattern to replace all occurrences of a specified pattern with a replacement string.

For example,

  1. We define a string variable str with the value 'The quick brown fox jumps over the lazy dog'.
  2. We use the replaceAll() method with a regular expression to replace all occurrences of vowels with '*'.
  3. The result is stored in the variable newStr.
  4. We log newStr to the console using the console.log() method.

JavaScript Program

const str = 'The quick brown fox jumps over the lazy dog';
const newStr = str.replaceAll(/[aeiou]/ig, '*');
console.log(newStr);

Output

Th* q**ck br*wn f*x j*mps *v*r th* l*zy d*g

3 Using replaceAll() method with a function

In JavaScript, the replaceAll() method can use a function as the replacement. The function is invoked for each match found, and its return value is used as the replacement.

For example,

  1. We define a string variable str with the value 'apple, banana, cherry'.
  2. We use the replaceAll() method with a function to replace each fruit with its uppercase version.
  3. The result is stored in the variable newStr.
  4. We log newStr to the console using the console.log() method.

JavaScript Program

const str = 'apple, banana, cherry';
const newStr = str.replaceAll(/\b\w+\b/g, function(match) {
  return match.toUpperCase();
});
console.log(newStr);

Output

APPLE, BANANA, CHERRY

Summary

In this JavaScript tutorial, we learned about replaceAll() method of String: the syntax and few working examples with output and detailed explanation for each example.