A jQuery closure for basic encapsulation. For more info, see https://philkurth.com.au/tips/use-closures-for-basic-encapsulation-when-writing-jquery/

jquery-closure-example.js

(function ($, window, document, undefined)
{
    // Write your jQuery here. Any JavaScript you write in here 
    // is scoped so you don't have to worry about symbol names 
    // clashing with each other. 

    // You can define functions in here that are only available 
    // in this scope.
    function my_scoped_function(){ /* … */ }

})(jQuery, window, document);