Shortcode and automatic AJAX content reload immediately after page load - WordPress

div-update-ajax.php

<?php

/* Shortcode actualizado por Ajax */

//My shortcode that outputs the DIV and the necessary javascript (which should be external actually)
add_shortcode( 'my_shortcode' , 'my_shortcode_function' );
function my_shortcode_function() {
	ob_start();
	echo my_shortcode_function_content();
	?>
	<script type="text/javascript">
	jQuery(document).ready(function($) {
		if ( $( '#my_shortcode_div' ).length ) {
			$.ajax({
				url: '<?php echo admin_url( 'admin-ajax.php' ); ?>',
				type: 'get',
				data: {
					action: 'my_shortcode_ajax_action'
				},
				success: function(data) {
					$( '#my_shortcode_div' ).replaceWith( data );
				},
				fail: {
				}
			});
		}
	});
	</script>
	<?php
	return ob_get_clean();
}
//The actual DIV content
function my_shortcode_function_content() {
	ob_start();
	?>
	<div id="my_shortcode_div">
		This is the shortcode content.
		<br/>
		Date / time: <?php echo date( 'Y-m-d H:i:s' ); ?>
		<br/>
		Random number: <?php echo rand( 0, 1000 ); ?>
		<br/>
		Origin: <?php echo defined('DOING_AJAX') && DOING_AJAX ? 'AJAX' : 'Page load'; ?>
	</div>
	<?php
	return ob_get_clean();
}

//The Ajax action
add_action( 'wp_ajax_my_shortcode_ajax_action', 'my_shortcode_function_ajax' );
add_action( 'wp_ajax_nopriv_my_shortcode_ajax_action', 'my_shortcode_function_ajax' );
function my_shortcode_function_ajax() {
	echo my_shortcode_function_content();
	wp_die();
}