Using the toString() method on an array will return a string representation of the array:

const list = [1, 2, 3, 4]
list.toString()

Example:

The join() method of an array returns a concatenation of the array elements:

const list = [1, 2, 3, 4]
list.join()

We can pass a parameter to this method to add a custom separator:

a.join(', ')

Example: