Question

This may be a silly question, but why are function arguments in JavaScript not preceded by the var keyword?

Why:

function fooAnything(anything) {
  return 'foo' + anyThing;
}

And not:

function fooAnything(var anything) {
  return 'foo' + anyThing;
}

I have a feeling the answer is because that's what the Spec says but still…

Answer 1

It would be a redundant use of the var keyword. Items that appear in the parentheses that follow a function name declaration are explicitly parameters for the function.