Question

Possible Duplicate:
JavaScript: var functionName = function() {} vs function functionName() {}
Function declaration – Function Expression – Scope

I’ve learned about var a = 1, is defining a local variable, but talk about function, I thought It’s only available within the current scope as the var variable behave, what’s the difference between the following two code snippet?

function aPrint() {
console.log('a');
}

var a = function aPrent() {
console.log('a');

}

Answer 1

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refer http://www.dustindiaz.com/javascript-function-declaration-ambiguity/

1. function aPrint() {}
   Declares a function (but does not execute it).
   It will usually have some code between the curly brackets.

2. var a = aPrint()
   Declares a variable, invokes a function (aPrint) and sets the value of aPrint to the return of the function.

3. var a= new aPrint()
   Creates a new instance of an object based on the aPrint function. So the variable is now an Object, not just a string or a number.

Objects can contain indexed strings, numbers and even functions, and you can add more stuff to them, they’re pretty awesome. The whole concept of Object Oriented Programming (OOP) is based on this.