Yii2 Ajax调用 [ 求助交流 ]

调用ajax怎么都实现不了， 下面是我的代码，请各位高手帮我看看

View
<input type="button" id="test" value="submit"  >
$this->registerJs('
  $("#test").click(function() {
         //alert("aa");
         var id = "1";
        var val = "huangjiyun";
        var href = \'/yii2test2/frontend/web/index.php?r=city/index3\';
        $.ajax({
            type  : "POST",
            url   : href,
            dataType:"json",
            data:{"id":id,"val":val},
           success:function(json) {
                alert("success");
            }

        });


  } );
 ');

 ?>

controller

public function actionA_action()
{
    if(Yii::$app->request->isAjax) {
        $para = Yii::$app->request->post();
        $val= explode(":", $para['val']);
        $val= $val[0];
 
    }
}