Question

I thought one of the point of functions in javascript was to provide scope. Things defined in a function were only available inside the function.

function cat(name) {
    talk = function() {
        alert(" say meeow!" )
    }
} 

talk()

I would expect the above code to fall over because talk should not be visible. But it is, why?

Answer 1

It is because you didn’t declare it with a var keyword.

If you don’t use the var keyword, it will be in the global scope. If you do use var, it will be in the function scope:

function cat(name) {
  //anonymous function assigned to the local variable talk
  var talk = function() {
    alert(" say meeow!" )
  };
}

You can declare named functions without the var keyword, and they will still be in the local scope:

function cat(name) {
  //local talk function
  function talk() {
    alert(" say meeow!" )
  };
}