Yii2. How to send data via ajax?

Question

Yii

Good day to all.
I'm trying to figure out how to pass data from a view to a controller using ajax.
Here's what I get:
There is JS code in the view:

<?php
$js=<<<JS
   $("#testBut").on("click", function(e) {
         $ajax({
         	url : '/analytica',
         	type : 'POST',
         	data : {dat : 'qwe', '<?= Yii::$app->request->csrfParam; ?>' : '<?= Yii::$app->request->getCsrfToken() ?>'},
         	success : function(res){
         		console.log(res);
        },
      error : function(){
        alert('Ошибка при отправке данных: перезагрузите страницу!');
      }
         })
          return false;
      })
JS;
$this->registerJs($js);
?>

In the controller, the following code:

public function actionIndex()
    {
    	if(\Yii::$app->request->isAjax){
      return 'Запрос принят';
    }
        return $this->render('index');
    }

On the Internet, I read that the data may not be sent due to the fact that I do not pass csrf , which is why the code was added to JS

'<?= Yii::$app->request->csrfParam; ?>' : '<?= Yii::$app->request->getCsrfToken() ?>'

But since the code is not converted, but is displayed exactly as it is written - I understand that somewhere I turned the wrong way.

I'd be grateful if you could give me some direction on how to proceed.

Answer 1

The issue was resolved very simply.

$this->registerJs('$("#testBut").on("click", function(e) {
         $.ajax({
         	url: "'.\yii\helpers\Url::toRoute(['','id'=>$someid]).'",
         	type : "POST",
         	data : {dat : "qwe"},
         	success : function(res){
         		console.log(res);
        },
      error : function(){
        alert("Ошибка при отправке данных: перезагрузите страницу!");
      }
         })
        return false;  
      })');

Can anyone tell me how to use php code when generating JS code in this way:

$js=<<<JS
...
JS;
$this->registerJs($js);