Join() Function

The join() method is an array method in Google Apps Script that joins all the elements of an array into a string. It takes an optional argument that specifies the separator between each element in the resulting string. By default, the separator is a comma (,), but you can use any character or string as the separator.

For example, let’s say we have an array of country names:

var countries = ["USA", "Canada", "Mexico", "Brazil", "Argentina"];

We can use the join() method to join all the elements of the array into a single string, separated by commas:

var countryList = countries.join();

In this example, we call the join() method on the countries array and assign the resulting string to a variable called countryList. The value of countryList will be the string "USA,Canada,Mexico,Brazil,Argentina".

We can pass it as an argument to the method if we want to use a different separator. For instance, if we want to separate the country names with a hyphen (-), we can do the following:

var countryList = countries.join("-");