IIFE (Immediately Invoked Function Expression)

(function () {

})();

This is a nameless function which immediately invokes itself.

What this does is supports modularization by wrapping the content within a scope—preventing global namespace pollution & helping with separation of concerns.

Document-Ready Function

$( document ).ready(function() {
    console.log( "ready!" );
});

Document-Ready IIFE

(function($) {
  $(function() {
  });
})(jQuery);

Check if element exists before running script

var check = document.getElementsByName("ELEMENT");
if(check.length != 0)
{
  // Do something
}