why do you use a ready function in jquery code example

Example 1: jquery document ready

// jQuery document ready
$(document).ready(function() {
    
});

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.
});