Controller::beforeRender in Yii2

I’m migrating an old app developed in Yii1 to Yii2.

I used to have a array in the controller that was storing all the variables that I would need to send to the frontend as a JavaScript:

public $jsVars;

public function toJSObject($params){

    $this->jsVars = array_merge($this->jsVars, $params);


private function printJSVarsObject(){

  //convert my php array into a js json object


When I needed a variable to be exposed in Javascript, I would just use $this->toJSObject, in the View or in the Controller.

Then, in the controller I also used to have:

public function beforeRender($view){



In Yii2, I had to configure the View component with a custom View and then attach an event:

namespace app\classes;

use yii\base\Event;

use yii\helpers\Json;

Event::on(\yii\web\View::className(), \yii\web\View::EVENT_END_BODY, function($event) {



class View extends \yii\web\View {

    public $jsVars = [];

    public function addJsParam($param){

        $this->jsVars = array_merge($this->jsVars, $param);


    public function registerJSVars() {


            "var AppOptions= " . Json::htmlEncode($this->jsVars) . ";",






But, having the event outside the class seems weird to me. Also, while I’m in the controller, I won’t be able to use my former approach using this method.

Obviously, I’m missing something, or my approach is just incorrect.

How do you guys do that?