JavaScript Program Replace Specific Words with Another Word in a String using Regular Expressions

In this article, we are going to learn about replacing specific words with another word in a string using regular expressions. Replacing specific words with another word in a string using regular expressions in JavaScript means searching for all occurrences of a particular word or pattern within the text and substituting them with a different word or phrase, considering possible variations and multiple instances.

There are several methods that can be used to replace specific words with another word in a string using regular expressions in JavaScript, which are listed below:

• Using String.replace()
• String.split() and Array.join() methods

We will explore all the above methods along with their basic implementation with the help of examples.

Approach 1: Using String.replace()

In this approach, we are Using String.replace() with a regular expression allows you to find and replace specific words or patterns within a string efficiently, enabling global replacements for all occurrences of the target.

Syntax:

function replaceWord(val1, val2, val3) {
    let regex = new RegExp(val2, 'g');
    return val1.replace(regex, val3);
};

Example: In this example, The replaceWord function uses a regular expression to replace all occurrences of ‘gfg’ with ‘GeeksforGeeks’ in the input text, demonstrating word replacement.

Javascript

function replaceWord(val1, val2, val3) {
    let regex = new RegExp(val2, 'g');
    return val1.replace(regex, val3);
}

let inputText =
    "gfg is a computer science portal.";
let result =
    replaceWord(inputText, 'gfg', 'GeeksforGeeks');
console.log(result);

Output

GeeksforGeeks is a computer science portal.

Approach 2: String.split() and Array.join() methods

In this approach, Using String.split() to split a string into words, mapping and replacing specific words, and finally using Array.join() to rejoin the modified words into a new string efficiently.

Syntax:

let words = str1.split(/\s+|\W+/);

Example: In this example, we split the string into words while removing punctuation, compare each word case-insensitively, and replace occurrences of ‘gfg’ with ‘GeeksforGeeks’, then rejoin the modified words.

Javascript

let str1 = "gfg, a Computer science Portal.";
let word1 = 'gfg';
let changeWord = 'GeeksforGeeks';

// Split the string into words and remove punctuation
let words = str1.split(/\s+|\W+/);

let replacedWords = words.map((word) =>
    (word.toLowerCase() === word1.toLowerCase()
    ? changeWord : word));

let result = replacedWords.join(' ');

console.log(result);

Output

GeeksforGeeks a Computer science Portal