if jquery ready code example

Example 1: document ready without jquery

document.addEventListener("DOMContentLoaded", function(event) { 
  //we ready baby
});

Example 2: jquery document ready

The .ready() method is typically used with an anonymous function:
$( document ).ready(function() {
  // Handler for .ready() called.
});

Which is equivalent to the recommended way of calling:
$(function() {
  // Handler for .ready() called.
});