Run javascript code after wp_login hook?

Question

after using the wp_login hook, is it possible to add a snippet of javascript code to the page seen immediately after the login in wordpress?

I want to use this top implement a notification system that notifies the user when they login.

Answer 1

The typical method to store pending action in WordPress is to set short-lived transient (set_transient()). Since this would need to distinguish between users you can incorporate user info as part of transient key or use different storage API, such as user option (update_user_option()), instead.

Answer 2

I would do something like this:

function wpse38285_wp_login( $user_login ) {
    set_transient( $user_login, '1', 0 );
}
add_action( 'wp_login', 'wpse38285_wp_login' );

function wpse38285_wp_footer() {
    global $current_user;
    get_currentuserinfo();

    if ( ! is_user_logged_in() )
        return;

    if ( ! get_transient( $current_user->user_login ) )
        return;

    $js = <<<JS
    <script type="text/javascript">
        jQuery('<div />')
            .html('<p>You are now logged in as <strong>$current_user->user_login</strong><br /><small>(click to close)</small></p>')
            .css({
                'width': '300px',
                'position': 'absolute',
                'left': '50%',
                'marginLeft': '-160px',
                'top': '100px',
                'backgroundColor': '#cdcdcd',
                'textAlign': 'center',
                'padding': '10px'
            })
            .appendTo('body')
            .on('click', function() { jQuery(this).remove(); } );
    </script>
JS;
    echo $js;
    delete_transient( $current_user->user_login );
}
add_action( 'wp_footer', 'wpse38285_wp_footer' );

Set a never-expiring transient for the user after logging on. If a transient is set for that user, inject some JavaScript code and delete the transient.