Why we should put JavaScript code inside an IIFE?

Question

I have recently started the Angular.js tutorial which shows code written inside of an Immediately Invoked Function Expression (IIFE). I was wondering why should we put our JavaScript inside such a construct? Is it because of security reasons?

Eg: Why this:

(function(){
    var app = angular.module("AppName", [])
})();

And not just this:

var app = angular.module("AppName", [])

Sorry, didn't know that IIFE was another way of calling it. I'll vote to close the question. — siannone, Sep 19 '14 at 16:50
It's all good, I just wanted to clarify terms, and the other chap noticed that with the clarified terms this had already been asked. A closure is really something different than an IFFE, though IIFE's are a way to create a closure. — JAAulde, Sep 19 '14 at 16:51
Notice, that the examples are doing totally different things. — Teemu, Sep 19 '14 at 17:02

score 1 · Accepted Answer · answered Sep 19 '14 at 16:38

1

Having app as a global variable could cause conflicts

answered Sep 19 '14 at 16:38

Mark

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score 1 · Answer 2 · answered Sep 19 '14 at 16:38

1

It prevents you from creating a global variable.

answered Sep 19 '14 at 16:38

Brian Lewis

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But then I guess it would be useless if I use require.js right? – siannone Sep 19 '14 at 16:39
1

pretty much, because requirejs will wrap it in a closure of its own. – Brian Lewis Sep 19 '14 at 16:40

Why we should put JavaScript code inside an IIFE?

2 Answers2