Yii2_ configuration file 1_ define Yii\web\response components and listen

Configuration is to define the properties of a class, the first layer is to define the properties of the app, the components are to define the properties of each component, to listen to events, we are not defining attributes, the wording is this:

return[application's configuration' Components ' =[Configuration of other components' Response ' = [            //Focus here, first write on plus a space, and then write the event's tag value' On beforesend ' =function($event){                if(is_string($event->sender->data)) {                    $event->sender->data = ' The following is HTML content: '.$event->sender->data; }            }        ],    ],];

Yii2_ configuration file 1_ define Yii\web\response components and listen