This code is basic and for beginners.
Usually, you can see solutions but not how to wrap jQuery code to start writing it for WordPress or Oxygen.
The outer Javascript function is known as an anonymous function and jQuery is wrapped at the end, so is therefore aliased or bound to the $ selector, so in the inner function the jQuery shorthand document does not need to be aliased.
Code was taken from wpbeaches.com
Big thanks to Sridhar Katakam and Supa Mike
Version bellow was giving me error in a couple of occasions
(function($){
$(function() {
// Code goes here
});
})(jQuery);