Yii2视图文件中的jQuery

这是我的表格代码：

<?= $form->field($model, 'stdclass_id')->dropDownList($stdclassArray,
    ['prompt' => 'Select','id' => 'selectedclass'])->label('Class') ?>

<?= $form->field($model, 'session_id')->dropDownList($sessionArray,
    ['prompt' => 'Select', 'id' => 'selectedsession',])->label('Session') ?>

<?= $form->field($model, 'roll_no')->textInput(['maxlength' => true, 'id' => 'roll']) ?>

这是表单的jQuery部分：

$script = <<< JS

$('#selectedsession').on('change',function(){
    var value1 = document.getElementById("selectedclass").value;
    var value2 = document.getElementById("selectedsession").value;

    $.ajax({
        url: '<?php echo Yii::$app->request->baseUrl. '/enrollment/rollno' ?>',
        type: "POST",
        data: { value1: value1, value2 : value2 },
        success: function(data) {
            var abc = data;
            $("#roll").val(abc);
        }
    });
});

JS;

---

$script=从这里提取php变量

$baseUrl = Yii::$app->request->baseUrl;

$script = <<< JS

$('#selectedsession').on('change',function(){
var value1 = document.getElementById("selectedclass").value;
var value2 = document.getElementById("selectedsession").value;

$.ajax({

             url: '{$baseUrl}/enrollment/rollno',
             type: "POST",
             data: { value1: value1, value2 : value2 },
             success: function(data) {
                 var abc = data;
                $("#roll").val(abc);
             }
         });
});

JS;

$baseUrl=Yii:：$app->request->baseUrl；
$script=从这里提取php变量

$baseUrl = Yii::$app->request->baseUrl;

$script = <<< JS

$('#selectedsession').on('change',function(){
var value1 = document.getElementById("selectedclass").value;
var value2 = document.getElementById("selectedsession").value;

$.ajax({

             url: '{$baseUrl}/enrollment/rollno',
             type: "POST",
             data: { value1: value1, value2 : value2 },
             success: function(data) {
                 var abc = data;
                $("#roll").val(abc);
             }
         });
});

JS;

$baseUrl=Yii:：$app->request->baseUrl；
$script=I还包括使用yii\helpers\Url；我还包括使用yii\helpers\Url；谢谢你，伙计。你让我开心：）谢谢你，伙计。你让我开心：）