Magento 2 How to add core or custom JavaScript file

There are so many ways we can include javascript in Magento 2.

Example: 1

   require(['jquery', 'jquery/ui'], function($){ 
     //your js code here  
   });

Example: 2

   require(['jquery'],function($){
     $(window).load(function() {
         alert('jquery working');
     });
   });