Wordpress Ajax code to perform any Function using Ajax Easily

WP Ajax Example

<?php
/********************************************************************************/
/*** Wordpress Ajax code to perform any Function using Ajax Easily***/
/********************************************************************************/


add_action( 'wp_footer', 'my_action_javascript' );
function my_action_javascript() { ?>
	<script type="text/javascript" >
	/* Make this document ready function to work on click where you want */
	jQuery(document).ready(function($) {
		
		/* In front end of WordPress we have to define ajaxurl */	
		var ajaxurl = '<?php echo admin_url('admin-ajax.php'); ?>';
		
		/* You can get this value from some hidden field or div */		
		var postid = 1;   

		/* get this email from some input field */
		var email = "[email protected]";
		
		var data = {
			'action': 'my_action',
			'email_to_add' : email,
			'postid' : postid 
			
		};

		$.post(ajaxurl, data, function(response) {
			alert(response);
		});
	});
	</script> <?php
}


add_action( 'wp_ajax_my_action', 'my_action_callback' );
add_action( 'wp_ajax_nopriv_my_action', 'my_action_callback' );

function my_action_callback() {

	$postid =  $_POST['postid'];
	$email = $_POST['email_to_add'];
	
	/* get existing emails from post meta */
	$prev_emails = get_post_meta($postid,'emails_to_notify',true);

	/* get the title of post */
	$post_title = get_the_title($postid);
	
	/* concatenate new email with previous if they exist */	
	if($prev_emails)
	$emails = (string) $prev_emails . ',' . (string) $email ; 
	else
	$emails = (string) $email;
	
	/* update emails in post meta */	
	update_post_meta( $postid ,'emails_to_notify', $emails );

	/* send response to know what is really going on */	
	echo  " Email added to post with tiltle: ". $post_title . "\n New email added: ". $email ."\n Following emails are there: " . $emails ;

	die(); // this is required to terminate immediately and return a proper response
	
}