Empty post yii2, what?

Question

Yii

What's wrong with this framework?!
I am sending a js array containing several numbers to the server in a Yii2 controller. The result is an empty $_POST. Moreover, the same code works fine on another site.

var xhr = new XMLHttpRequest();
        xhr.open('POST', action, true);
        xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
        xhr.send(data);
        xhr.onloadend = function() {
            console.log(xhr.response);
        }

public function actionActivate()
    {
        Yii::$app->response->format = Response::FORMAT_JSON;
        return Yii::$app->request->post();
    }

Answer 1

you must specify in the settings

'components' => [
       'request' => [
            'parsers' => [
                'application/json' => \yii\web\JsonParser::class,
            ]
        ],
]

Answer 2

_csrf is passed?

Answer 3

$_POST gets something that can be parsed, so look in php://input