JavaScript String concat() Method

The concat() method in JavaScript join or concatenate two or more strings together. It does not change the existing strings and returns a new string. This method efficiently combines multiple strings into one, ensuring the original strings remain unchanged.

Syntax

str1.concat(str2, str3, str4,......, strN)

Parameters

• str1, str2, ..., strN: This method accepts the string paramters that need to be joined together. The number of arguments to this function is equal to the number of strings to be joined together.

Note: If the parameters are not of String type, then first it converted to string before concatenating the strings.

Return value

Returns a new string that is the combination of all the different strings passed to it as the argument.

Example 1: Join Two Strings with concat() Method

The string "str" is initialized with the value "Welcome". Then concat() method is used on str to combine it with "Geeks".

// JavaScript String concat() method
// to merge strings together

// First string
let str = "Welcome";

// Joining the strings together
let concatStr = str.concat(" Geeks");

console.log(concatStr);

Welcome Geeks

Example 2: Concatenating Multiple Strings with concat() Method

The concatenates strings str1, str2, and str3 together. The result1 combines them without spaces, while result2 concatenates them with spaces.

let str1 = 'Geeks'
let str2 = 'For'
let str3 = 'Geeks'

// Concating all the strings together without spaces
let result1 = str1.concat(str2, str3)
console.log('Result without spaces: ' + result1)

// Concating all the strings together with spaces
let result2 = str1.concat(' ', str2, ' ', str3)
console.log('Result with spaces: ' + result2)

Result without spaces: GeeksForGeeks
Result with spaces: Geeks For Geeks

Eample 3: Concatenate with Empty Strings

You can use the concat() method with empty strings to control the formatting or add spaces dynamically

const str1 = "Hello";
const str2 = "";

const str = str1.concat(str2);

console.log(str);

Hello

We have a complete list of Javascript string methods, to check those please go through this Javascript String Complete reference article.

Supported Browsers

• Chrome 1
• Edge 12
• Firefox 1
• Opera 4
• Safari 1