JavaScript, like any good language, has the ability to join 2 (or more, of course) strings.

How?

We can use the + operator.

If you have a string name and a string surname, you can assign those too the fullname variable like this:

const fullname = name + surname

If you don’t want to instantiate a new variable, you can use the += operator to add the second string to the first:

name += surname

Alternatively you can also use the concat() method of the String object, which returns a new string concatenating the one you call this method on, with the argument of the method:

const fullname = name.concat(surname)

I generally recommend the simplest route (which also happen to be the faster) which is using the + (or +=) operator.