JavaScript add strings

last modified February 17, 2021

JavaScript add strings tutorial shows how to concatenate strings in JavaScript.

In JavaScript, 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

In this tutorial, we have showed several ways of concatenating strings in JavaScript.

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