How to add template identifier in Yii2 HTML output

Sometimes it’s nice to know which template is currently rendered, just by looking into HTML source. It saves a lot of time if your application is really big.

To add such behaviour to your app simply edit your Yii2 config file (in my case it’s config/web.php), it is located in components section:

File: web.php
-------------

 [
        'view' => [
            'on afterRender' => function ($event) {
                // Check if this is not a layout file
                if( preg_match( '/layouts/', $event->viewFile ) == 0 ) {
                    /**
                     *  Add template info.
                     */

                    /** @var $event yii\base\ViewEvent */
                    $event->output = "\n" . $event->output . "\n";
                }
            },
        ], 
    ],
];