Function overloading in Javascript - Best practices

What is the best way(s) to fake function overloading in Javascript?

I know it is not possible to overload functions in Javascript as in other languages.
If I needed a function with two uses foo(x) and foo(x,y,z) which is the best / preferred way:

1. Using different names in the first place


2. Using optional arguments like y = y || 'default'


3. Using number of arguments


4. Checking types of arguments



5. Or how?