javascript - How do these patterns differ? -

how this:

var obj = obj || {};  obj.something = (function() {      function something() {      };      something.prototype.somemethod = function() {      };      return something;  })(); 

differ this:

obj.something = function() {  };  obj.something.prototype = {  }; 

how patterns differ? when use 1 on other?

the main reason why use way teacher recommends may define other variables , functions wouldn't exposed in global scope.

for example :

obj.something = (function() {     var sum = 0;     function something() {     };     something.increment = function(){ sum++ };     something.getsum = function(){ return sum };         return something; })(); 

here sum isn't public , doesn't pollute global namespace.

other that, both patterns pretty similar. it's idea accustomed iife pattern when, do, try know why it's useful , not apply it.