The JavaScript join() method is a handy tool for working with arrays. It allows you to concatenate the elements of an array into a single string, using a specified separator. In this tutorial, we’ll explore how to use the join() method with easy-to-understand examples.

Before diving into the tutorial, make sure you have a basic understanding of JavaScript and arrays. If you’re new to JavaScript, consider learning the fundamentals first.

join method Javascript Syntax

The join() method has the following syntax:

  • array: The array you want to join.
  • separator (optional): A string that specifies how the array elements should be separated in the resulting string. If omitted, the array elements will be separated by a comma.

Example 1: Javascript joining strings

Let’s start with a basic example of join string in JavaScript:

const fruits = ["apple", "banana", "cherry"];
const joinedFruits = fruits.join();

console.log(joinedFruits); //"apple,banana,cherry" 

In this example, the join() method joins the elements of the fruits array using the default separator, which is a comma.

Example 2: Custom Separator in join method

You can specify a custom separator as an argument to the join() method:

const colors = ["red", "green", "blue"];
const joinedColors = colors.join(" | ");

console.log(joinedColors); // "red | green | blue" 

By passing " | " as the separator, we get a string where the array elements are separated by a vertical bar and space.

Example 3: Join an Empty Array JavaScript

The join() method can also be used with an empty array:

const emptyArray = [];
const result = emptyArray.join("-");

console.log(result); // "" 

In this case, the result is an empty string, as there are no elements in the array.

Example 4: Join Array in JavaScript

You can join arrays of numbers as well:

const numbers = [1, 2, 3, 4, 5];
const joinedNumbers = numbers.join(" + ");

console.log(joinedNumbers); // "1 + 2 + 3 + 4 + 5" 

Here, we’re using the join() method to concatenate the numbers with a ” + ” separator.

Example 5: JavaScript Joining Mixed Data Types

You can join arrays containing mixed data types, such as strings and numbers:

const mixedData = ["apple", 3, "banana", 5, "cherry"];
const joinedMixedData = mixedData.join(" | ");

console.log(joinedMixedData); // "apple | 3 | banana | 5 | cherry" 

The join() method works seamlessly with mixed data types, converting them all to strings.


The join() method is a simple yet powerful tool for concatenating array elements into a string. It’s easy to use and versatile, allowing you to specify custom separators or use the default comma. It’s especially helpful when you need to format data for display or when working with dynamic content.