JavaScript Program to Replace Characters of a String
Last Updated :
13 Mar, 2024
Given a String the task is to replace characters of String with a given String in JavaScript.
Examples:
Input: Str = Welcome to GfG
strRepl = GfG
newStr = Geeks
Output: Welcome to Geeks
Approaches to Replace Characters of a String in JavaScript
Using map() & split() method to replace characters from String
In this approach, split(‘ ‘) is used to split the string into an array of words. Then, map() is used to iterate over each word in the array. If the word is equal to oldWord, it is replaced with newWord; otherwise, the word remains unchanged. Finally, join(‘ ‘) is used to join the array back into a string
Example: Here we will split the given string “Hello user, welcome to GeeksforGeeks” and replace the “Hello” with “Hi”.
Javascript
const str = "Hello user, welcome to GeeksforGeeks";
oldWord='Hello';
newWord='Hi'
const replacedString=str.split(' ').map(word => word === oldWord ? newWord : word).join(' ');
console.log(replacedString);
OutputHi user, welcome to GeeksforGeeks
Using String replace() Method to replace characters from String
JavaScript string.replace() method is used to replace a part of the given string with another string or a regular expression. The original string will remain unchanged.
Example: Here we will replace the “GfG” with “Geeks” on the given string “Welocome to GfG”.
Javascript
// JavaScript program to Replace
// Characters of a string
const str = 'Welcome to GfG';
const replStr = 'GfG';
const newStr = 'Geeks';
const updatedStr = str.replace(replStr, newStr);
console.log(updatedStr);
Using Regular Expression to replace characters from String
To replace all occurrences of a string in JavaScript using a regular expression, we can use the regular expression with the global (g
) Flag.
Example: In this example we will replace “Welcome” with “Hello” in the given string “Welcome GeeksforGeeks, Welcome geeks”.
Javascript
const str = 'Welcome GeeksforGeeks, Welcome geeks';
const searchString ="Welcome";
const replacementString ="Hello";
let regex = new RegExp(searchString, 'g');
let replacedString =
str.replace(regex, replacementString);
console.log(replacedString);
OutputHello GeeksforGeeks, Hello geeks
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