The purpose of (function(){})() in javascript

Question

What's the purpose of doing

(function(){
   console.log('holla at world');
})();

instead of

console.log('holla at world');

Is there an example where something has to be done using the first case.

Answer 1

(function(){
   console.log('holla at world');
})() 

It's Immediately invoking function expression(IIFE) , the point of using IIFE's is to stop global scope pollution.