Javascript Passing Parameters With Quotes

we will see a way in which a function body can get at the whole list of arguments it was passed (see “Rest Parameters” on page 74). This is helpful because it makes it possible for a function to accept any number of arguments.

When you pass a primitive value it is copied into the parameter. We call this “passing by value.” So if you change the value of the parameter in your function body it has no affect on our original argument’s value. The exception to this is passing an array or object, and we’ll get to that in a bit.