Function Declarations vs Function Expressions

gistfile1.js

//function declaration
function hola(){
}

//function expresion
var hola = function(){
}

//named function expression
var hola = function hola(){
}

//function expression via group operator
(function(){});

//named function expression
(function hola(){});

//named function expression via operator prefixing
!function hola(){
}

//named function expression via operator prefixing
+function hola(){
}