JavaScript String.replace() Method

1. Syntax of JavaScript string.replace():
2. Example Codes: Use the string.replace() Method to Replace a String
3. Example Codes: Use the string.replace() Method to Replace a String With a Regular Expression
4. Example Codes: Use the string.replace() Method to Replace a String With a Regular Expression Case Sensitivity

In JavaScript, the string.replace() method returns a new string. It first searches the given value from a string and replaces it with the new value.

A value, substring, or regular expression can be used as searches.

Syntax of JavaScript string.replace():

let newString = string.replace(searchValue, newValue)

Parameters

Return

The string.replace() method returns a new string where the new value replaces the search value.

Important: The string.replace() method will return the result. That means it does not change the actual string; you must declare a new variable to store the result.

Example Codes: Use the string.replace() Method to Replace a String

let string = 'The more I read, The more I learn'
let newString = string.replace('I', 'you')

console.log(newString)

Output:

The more you read, The more I learn

We passed the value I as the search value and you as the new value. That means I will replace the string with you.

This method replaced the first portion of the string but did not replace it globally. We must use the regular expression to replace a value from the string globally.

Example Codes: Use the string.replace() Method to Replace a String With a Regular Expression

let string = 'The more I read, The more I learn'
let newString = string.replace(/I/g, 'you')

console.log(newString)

Output:

The more you read, The more you learn

We wrapped I with a regular expression and used the flag -g to represent the global. As a result, the value I is replaced everywhere in the string with the value you.

Example Codes: Use the string.replace() Method to Replace a String With a Regular Expression Case Sensitivity

let string = 'The more I read, The more i learn'
let newString1 = string.replace(/I/g, 'you')
let newString2 = string.replace(/I/gi, 'you')

console.log(newString1)
console.log(newString2)

Output:

The more you read, The more i learn
The more you read, The more you learn

First, we provided the flag -g to replace the string globally. But it did not work because of case sensitivity.

Second, we again provided the flag -g to replace the string globally, but this time we provided another flag -i to make it case insensitive. As a result, this method replaced all the values.