Insert custom fields at user registration v2

index.php

<?php
/**
 * Plugin Name:	Custom user registration fields
 * Plugin URI:	http://yoda.neun12.de
 * Description:	Add custom fields to the user registration
 * Version: 	0.1
 * Author: 		Ralf Albert
 * Author URI: 	http://yoda.neun12.de
 * Text Domain:
 * Domain Path:
 * Network:
 * License:		GPLv3
 */

add_action(
	'plugins_loaded',
	array( 'WP_Custom_User_Registration_Fields', 'init' ),
	10,
	0
);


class WP_Custom_User_Registration_Fields
{

	/**
	 * Textdomain
	 * @var string
	 */
	const WP_CURF_L10N = 'wp_curf_l10n';

	/**
	 * Key for metadata
	 * @var string
	 */
	const META_KEY = 'department';

	/**
	 * Key for post array
	 * @var unknown
	 */
	const POST_KEY = 'department';

	/**
	 * Legend for field
	 * @var array
	 */
	protected static $legend = array();

	/**
	 * Table markup
	 * @var string
	 */
	protected static $table =
		'<h3>%1$s</h3>
		<table class="form-table">
			<tr>
				<th>
					<label for="%2$s">%1$s</label>
				</th>
				<td>
					<input type="text" name="%2$s" id="%2$s" value="%3$s" class="regular-text" />
					<br />
					<span class="description">%4$s</span>
				</td>
			</tr>
		</table>';

	/**
	 * Initialisation
	 * Defines label and description, adding hooks
	 */
	public static function init(){

		self::$legend = array(
				'label'			=> __( 'Department', self::WP_CURF_L10N ),
				'description'	=> __( 'Please specify the department to which the user belongs.', self::WP_CURF_L10N ),
				'postkey'		=> self::POST_KEY
			);

		self::add_hooks();

	}

	/**
	 * Adding needed action hooks, enqueueing javascript
	 */
	protected static function add_hooks(){

		add_action(
			'admin_print_scripts-user-new.php',

			function (){

				wp_enqueue_script(
					'add_custom_user_registration_field',
					plugins_url( 'wp_curf.js', __FILE__ ),
					array( 'jquery' ),
					false,
					true
				);

				wp_localize_script(
					'add_custom_user_registration_field',
					'wp_curf_l10n',
					self::$legend
				);

			}
		);

		foreach( array( 'show_user_profile', 'edit_user_profile' ) as $hook )
			add_action( $hook, array( __CLASS__, 'add_custom_user_profile_fields' ), 10, 1 );

		foreach( array( 'personal_options_update', 'edit_user_profile_update', 'user_register' ) as $hook )
			add_action( $hook, array( __CLASS__, 'save_custom_user_profile_fields' ), 10, 1 );
	}

	/**
	 * Output table
	 * @param object $user User object
	 */
	public static function add_custom_user_profile_fields( $user ){

		printf(
			self::$table,
			self::$legend['label'],
			self::POST_KEY,
			esc_attr( get_the_author_meta( self::META_KEY, $user->ID ) ),
			self::$legend['description']
		);

	}

	/**
	 * Saving field data
	 * @param integer $user_id User ID
	 * @return boolean bool	True on success, else false
	 */
	public static function save_custom_user_profile_fields( $user_id ){

		if( !current_user_can( 'edit_user', $user_id ) )
			return false;

		update_user_meta( $user_id, self::META_KEY, $_POST[self::POST_KEY] );

		return true;

	}

}

wp_curf.js

/**
 * jQuery part of Costum User Registration Field
 *
 *  @author		Ralf Albert
 *  @version	0.1
 */

jQuery( document ).ready(

    function($){

        var insertElements =
            '<tr class="form-field">' +
            '   <th scope="row"><label for="' + wp_curf_l10n.postkey + '">' + wp_curf_l10n.label + '</label></th>' +
            '   <td><input type="text" name="' + wp_curf_l10n.postkey + '" id="' + wp_curf_l10n.postkey + '" size="30"><br /><span class="description">' + wp_curf_l10n.description + '</span></td>' +
            '</tr>';

        $( '#createuser .form-table tbody' ).append( insertElements );

    }

);