Why are anonymous functions treated differently from named functions here? [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicates:

Javascript: var functionName = function() {} vs function functionName() {}

What is the difference between a function expression vs declaration in Javascript?

Today I stumbled upon the following phenomenon:

foo();
bar();

function foo()
{
    console.log("inside foo");
}

var b开发者_开发百科ar = function()
{
    console.log("inside bar");
}

FireBug complains with the following error message:

bar is not a function

Several tutorials claim that function f() and var f = function() are basically the same thing. Evidently, they are not, but what exactly is going on here?

---

Function declarations are available anywhere in the scope they're defined in, even before their physical definitions.

var bar = function() { ... }; is a normal variable that happens to hold a function. Like all other variables, it can only be used after its assigned.
(You cannot observe the future value of a variable)