Function overloading in Javascript - Best practices

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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?

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class="normal">Answer

The best
way to do function overloading with parameters is not to check the argument length or
the types; checking the types will just make your code slow and you have the fun of
Arrays, nulls, Objects, etc.

What most
developers do is tack on an object as the last argument to their methods. This object
can hold anything.

function
            foo(a, b, opts) {

 // ...
 if (opts['test']) { } //if
            test param exists, do something.. 
}


foo(1, 2,
            {"method":"add"});
foo(3, 4, {"test":"equals",
            "bar":"tree"});

Then
you can handle it anyway you want in your method. [Switch, if-else,
etc.]