JavaScript string replace() Method

In JavaScript, the replace() method is used to search for a specified substring in a string, and then replace it with another substring.

The replace() method does not change the original string.

replace() Method Syntax:

str.replace(value1, value2);

value1: is the regular expression that is to be replaced
value2: is a string that will replace the content of the given string.

Return Values:

It returns a new string with replaced items.

String replace() Method Example:

Below is an example of the string.replace() Method.

javascript

let string = 'GeeksForGeeks';

let newstring = string.replace('GeeksForGeeks', 'GfG');
console.log(newstring);

Output

GfG

Explanation:

A string string is assigned the value 'GeeksForGeeks'.
The replace() method is called on string, searching for the substring 'GeeksForGeeks' and replacing it with 'GfG'.
Since the entire string 'GeeksForGeeks' matches, it is replaced with 'GfG'.
The new string 'GfG' is assigned to the variable newstring.
newstring is logged to the console.

String replace() Method Example:

Here the contents of the string GeeksForGeeks will be replaced with gfg.

javascript

// Assigning a string

let string = 'GeeksForGeeks is a CS portal';

// Calling replace() method

let newstring = string.replace(/GeeksForGeeks/, 'gfg');
 
// Printing replaced string
console.log(newstring);

Output

gfg is a CS portal

Explanation:

A string string is assigned the value 'GeeksForGeeks is a CS portal'.
The replace() method is called on string, using a regular expression to match the substring 'GeeksForGeeks' and replace it with 'gfg'.
The first occurrence of 'GeeksForGeeks' in the string is replaced with 'gfg'.
The modified string is assigned to the variable newstring.
The replaced string newstring is logged to the console.

String replace() Method Example:

Below is an example of the string.replace() Method.

javascript

// Taking a regular expression
let re = /GeeksForGeeks/;
 
// Taking a string as input

let string = 'GeeksForGeeks is a CS portal';
 
// Calling replace() method to replace
// GeeksForGeeks from string with gfg

let newstring = string.replace(re, 'gfg');
 
// Printing new string with replaced items
console.log(newstring);

Output

gfg is a CS portal

Explanation:

A regular expression re is defined to match the substring 'GeeksForGeeks'.
A string string is assigned the value 'GeeksForGeeks is a CS portal'.
The replace() method is called on string, using the regular expression re to match the substring 'GeeksForGeeks' and replace it with 'gfg'.
The first occurrence of 'GeeksForGeeks' in the string is replaced with 'gfg'.
The modified string is assigned to the variable newstring.
The replaced string newstring is logged to the console.

We can also replace the same words at multiple places in a string. It is known as a global replacement.

String replace() Method Example:

This example explains replacing of various similar words in a string.

Javascript

// Assigning a string

let string = 'GeeksForGeeks is a CS portal.' +

    'In GeeksForGeeks we can learn multiple languages.' +

    'geeksForGeeks is a great place.';
 
// Calling replace() method

let newstring = string.replace(/GeeksForGeeks/g, 'Gfg');
 
// Printing replaced string
console.log(newstring);

Output

Gfg is a CS portal.In Gfg we can learn multiple languages.geeksForGeeks is a great place.

Explanation:

A multi-line string string is assigned with multiple occurrences of the substring 'GeeksForGeeks'.
The replace() method is called on string, using a regular expression with the global flag (/g) to match all occurrences of the substring 'GeeksForGeeks' case-sensitively and replacing them with 'Gfg'.
All occurrences of 'GeeksForGeeks' in the string are replaced with 'Gfg'.
The modified string is assigned to the variable newstring.
The replaced string newstring is logged to the console.

JavaScript string replace() Method – UseCase:

1. JavaScript String replaceAll() Method

The Javascript replaceAll() method returns a new string after replacing all the matches of a string with a specified string or a regular expression. The original string is left unchanged after this operation.