Storing WordPress user-selected password into database on registration

ts-swpdr.php

<?php
// Storing WordPress user-selected password into database on registration
// http://wp.me/p1Ehkq-gn

add_action( 'user_register', 'ts_register_extra_fields', 100 );
function ts_register_extra_fields( $user_id ){
	$userdata = array();

	$userdata['ID'] = $user_id;
	if ( $_POST['password'] !== '' ) {
		$userdata['user_pass'] = $_POST['password'];
	}
	$new_user_id = wp_update_user( $userdata );
}
?>