Is it wrong to define controller in angular wrapped in a function?

Question

I am looking at some code, and I see that it is written as shown below. It doesn't make sense to me. Is it wrong? Why is it written like that? Also, shouldn't the use strict; go at the very top, outside of the code?

(function() {
  'use strict';
  angular.module('itemList', [])
    .component('itemList', {
      templateUrl: 'item-list/item-list.component.html',
      controller: ['Item', ItemController]
  });

  function ItemController(Item) {
    //code
  }
}());

Answer 1

The reason it is wrapped in an IIFE is to keep all declarations like "use strict", functions and variables local to the scope contained within and not set in global namespace

If "use strict" was set global it can affect other unrelated code that my not comply and thus would cause unexpected errors to be thrown

Is it wrong to define controller in...

No. It is a best practice