Most people who only know some jQuery and little JavaScript in the browser scratch their head and wonder how this lame language can be run on a server, or better yet, how most of your front end can be run on this messed up language.

JavaScript hits the nail on head

Functions as first class citizens.

So what does this mean? Functions can be embedded inside other functions

    var outer = function embedded() {
        var inside = function() {
    var deep = 'variable inside a function, inside a function';
    };
    }

Notice how outer has a function inside it called inside, and inside the inside function is a variable deep? Did you see also how functions can be assigned to variables and even passed around.

I can even return a function from a function like this

function getMeSomeFunction() {
   return function() {
             alert('hey dude');
   };
}

var hello = getMeSomeFunction();
hello() ///   <---- this will alert 'hey dude'

Functions can be self executing like this

function() {
      alert('now man');
}();
/// Notice the () at the end of the function... when JavaScript parses this, it will run it too.

Hoisting is pretty awesome too… you can use a function in file even before it’s been declared because JavaScript hoists all functions to the top before going through the rest of the code.

Scoping in JavaScript is far out

JavaScript allows you to scope things pretty nice, so you can include variables and have access to values in parent functions. An example is in order.

var foo = 'bar';
function wrapper() {
 other();
}
function other() {
 alert(foo);
}
/// Notice that other() is hoisted so you can use it before it's been declared.
/// Notice that inside other, you have access to foo
/// Notice that inside wrapper you have access to other()

There are better examples of great scoping, but right now I’m at the end of my post… tata for now.