JavaScript Tutorials

JavaScript Array join()
Syntax & Examples

Array.join() method

The join() method of the Array class in JavaScript joins all elements of an array into a string. If no separator is provided, a comma (,) is used by default.

Syntax of Array.join()

There are 2 variations for the syntax of Array.join() method. They are:

1.
join()

This method joins all elements of an array into a string, using a comma (,) as the default separator.

Returns value of type String.

2.
join(separator)

Parameters

ParameterOptional/RequiredDescription
separatoroptionalA string to separate each pair of adjacent elements in the array. Defaults to a comma (,).

This method joins all elements of an array into a string, using the specified separator.

Returns value of type String.


✐ Examples

1 Using join() method with default separator

In JavaScript, we can use the join() method to join all elements of an array into a string with a comma (,) as the default separator.

For example,

  1. We define an array variable arr with elements [1, 2, 3, 4, 5].
  2. We use the join() method on arr without specifying a separator.
  3. The result is stored in the variable joinedString.
  4. We log joinedString to the console using console.log() method to see the joined string.

JavaScript Program

const arr = [1, 2, 3, 4, 5];
const joinedString = arr.join();
console.log(joinedString);

Output

1,2,3,4,5

2 Using join() method with a specified separator

We can use the join() method to join all elements of an array into a string with a specified separator.

For example,

  1. We define an array variable arr with elements ['apple', 'banana', 'cherry'].
  2. We use the join() method on arr with a hyphen (-) as the separator.
  3. The result is stored in the variable joinedString.
  4. We log joinedString to the console using console.log() method to see the joined string.

JavaScript Program

const arr = ['apple', 'banana', 'cherry'];
const joinedString = arr.join('-');
console.log(joinedString);

Output

apple-banana-cherry

3 Using join() method to join elements of an array of numbers with a space separator

We can use the join() method to join all elements of an array of numbers into a string with a space separator.

For example,

  1. We define an array variable numArr with elements [10, 20, 30, 40, 50].
  2. We use the join() method on numArr with a space as the separator.
  3. The result is stored in the variable joinedString.
  4. We log joinedString to the console using console.log() method to see the joined string.

JavaScript Program

const numArr = [10, 20, 30, 40, 50];
const joinedString = numArr.join(' ');
console.log(joinedString);

Output

10 20 30 40 50

Summary

In this JavaScript tutorial, we learned about join() method of Array: the syntax and few working examples with output and detailed explanation for each example.