What is the purpose of a self executing function in javascript?

Question

In javascript, when would you want to use this:

(function(){
    //Bunch of code...
})();

over this:

//Bunch of code...
         


        

Answer 1

Here's a solid example of how a self invoking anonymous function could be useful.

for( var i = 0; i < 10; i++ ) {
  setTimeout(function(){
    console.log(i)
  })
}

Output: 10, 10, 10, 10, 10...

for( var i = 0; i < 10; i++ ) {
  (function(num){
    setTimeout(function(){
      console.log(num)
    })
  })(i)
}

Output: 0, 1, 2, 3, 4...