how to use wordpress is_email() function in external file - php

Question

I'm coding an external php script that will be called from ajax in one of my WP page.
I want this script to be able to use wordpress functions.
This is what I've done so far:
require_once( $_SERVER['DOCUMENT_ROOT'] . '/wp-load.php' );
this allows me to access $wpdb object. Good. But I also want to use is_email() function and perhaps other native WP functions.
Right now I'm getting "Call to undefined function is_email()..." Fatal error.
Any advice appreciated

Answer 1

You are doing it wrong. WP is glad to provide the requested functionality for you. You should declare the handler in your plugin/theme functions.php file and register a handler for wp_ajax_my_action (the example is taken from WP Codex):
<?php
add_action( 'wp_ajax_my_action', 'my_action_callback' );
function my_action_callback() {
global $wpdb; // this is how you get access to the database
$whatever = intval( $_POST['whatever'] );
$whatever += 10;
echo $whatever;
wp_die(); // this is required to terminate immediately
// and return a proper response
}
More info.

Answer 2

Perhaps not the most elegant way but at least it worked for me.
in functions.php
add_action( 'wp_enqueue_scripts', 'localize_scripts');
function localize_scripts() {
wp_localize_script('jquery', 'urls', array( 'ajaxurl' => admin_url('admin-ajax.php') ));
}
inside the javascript
$.ajax({
url: urls.ajaxurl,
data: {
'action':'my_function',
'otherData': someString //variable
},
cache: false,
success: function() {},
error: function() {}
});
and again in functions.php
function my_function() {
// The $_REQUEST contains all the data sent via ajax
if ( isset($_REQUEST) ) {
$someString = $_REQUEST['otherData'];
echo $someString;
// Always die in functions echoing ajax content
die();
}
}
add_action( 'wp_ajax_my_function', 'my_function' );