jquery - JavaScript Statements in Global Scope -

i've written if statement in .js file outside function means in global scope, right?

here code snippet:-

if ((window != window.parent) && (document.referrer.indexof("facebook") != -1)) {     window.fbasyncinit = function() {         fb.init({             appid      : '...',             status     : true,             xfbml      : true         });     };      (function(d, s, id){         var js, fjs = d.getelementsbytagname(s)[0];         if (d.getelementbyid(id)) {return;}         js = d.createelement(s); js.id = id;         js.src = "//connect.facebook.net/en_us/all.js";         fjs.parentnode.insertbefore(js, fjs);     }(document, 'script', 'facebook-jssdk')); } 

is better write statement in following manner:-

(function() {     if ... })();  

what benefit of doing so? , these type of functions called?

they called immediately-executed functions (ief). hear them called self-executing functions, of misnomer; not self-execute, executed you, immediately.

the benefit protect global scope pollution. can prevent conflicts between libraries , plugins, say, , useful things strict mode, part of philosophy of contained in closure of sort.

i wouldn't have lots of iefs; consider having 1 whole script. alternatively can achieve global closure using object pattern.