JavaScript add strings

last modified October 18, 2023

In this article we show how to concatenate strings in JavaScript.

In JavaScript, a string is an object used to represent and manipulate a sequence of characters.

There are several ways of adding strings in JavaScript:

JavaScript add strings with + operator

The easiest way of concatenating strings is to use the + or the += operator. The + operator is used both for adding numbers and strings; in programming we say that the operator is overloaded.

let a = 'old';
let b = ' tree';

let c = a + b;

In the example, we add two strings with the + opeartor.

$ node add_string.js
old tree

In the second example, we use the compound addition operator.

let msg = 'There are';

msg += ' three falcons';
msg += ' in the sky';


The example builds a message with the += operator.

$ node add_string2.js
There are three falcons in the sky

JavaScript add strings with join

The join method creates and returns a new string by concatenating all of the elements of an array.

let words = ['There', 'are', 'three', 'falcons', 'in', 'the', 'sky'];

let msg = words.join(' ');

The example forms a message by concatenating words of an array.

$ node joining.js 
There are three falcons in the sky

JavaScript add strings with concat

The concat method concatenates the string arguments to the calling string and returns a new string.

Because the concat method is less efficient than the + operator, it is recommended to use the latter instead.

let a = 'old';

let c = a.concat(' tree');

The example concatenates two strings with the built-in concat method.

JavaScript add strings with string formatting

We can build JavaScript strings with string formatting, which is essentially another form of string addition.

let w1 = 'two';
let w2 = 'eagles';

let msg = `There are ${w1} ${w2} in the sky`;

The example builds a message using template literals.

$ node formatting.js 
There are two eagles in the sky


JS String documentation

In this article we have presented several ways of concatenating strings in JavaScript.


My name is Jan Bodnar and I am a passionate programmer with many years of programming experience. I have been writing programming articles since 2007. So far, I have written over 1400 articles and 8 e-books. I have over eight years of experience in teaching programming.

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