I'm confused by the most basic premise of JavaScript functions.

1) Why do I have to set year = newDate().getFullYear() and then return it?

All code within a function is within a code block ie the { }. Code within the block is only accessible within the block. year = newDate().getFullYear() assigns the year value to the year variable. You need to return it so when the method is called the year value will be assigned to the yearToday variable, if you don't return it yearToday will still be undefined.

2) I don't see how yearToday = getYear() is actually calling the function.

You are not setting yearToday equal to the getYear function. by adding the parenthesis ie () after the function name, you are now calling the function. And when you call a function you execute whats within the function. And what it is doing is returning the "year" so now yearToday is equal to what is return in the getYear function which is the "year" (new Date().getFullYear()).

Hope this helps.

We use functions so we don't have to repeat code everywhere. So in this example if you wanted to create a new variable "currentYear" you can assign is as follows currentYear = getYear(); which will return the "year" instead of having to type currentYear = new Date().getFullYear();

When you set a variable to equal a function, it runs that function, and whatever the functions returns becomes the value of that variable.

Returning the variable to the function just means that the function becomes whatever that variable inside it evaluates to.

Does that help?

I think one of the causes of confusion may be related to the Date().getFullYear() method. The line var year = new Date().getFullYear(); is actually calling on an entirely new method, different than the getYear() function that is the outer containing function.

The Date.getFullYear() method will return the four-digit full year. That returned value is then assigned to var year and is then returned by the getYear() function.