Why using self executing function? [duplicate]

Answer 1

There can be a couple of reasons.

The first one is protecting the scope, as the function creates a new scope.

Another one can be binding variables, for example

for (var i = 0; i < n; i++) {
   element.onclick = (function(i){
      return function(){
         // do something with i
     }
   })(i);
}