Yii2:让一个表单字段的值取决于另一个，如何编写ajax - Yii2 : let a form-filed‘s value depends on another,how to write ajax

Yii2 : let a form-filed‘s value depends on another,how to write ajax

如下所示，可以输入amount和fee-rate字段，但fee是自动设置的（fee=rate*amount），因此人们不会自己计算。

<div class="loanr" id="loan-rate"><?= $form->field($model, 'amount')?></div>
<div class="loanr" id="loan-rate"><?= $form->field($model, 'fee-rate')?></div>

如何更改此行：

<div class="loanr" id="loan-fee"><?= $form->field($model, 'fee')?></div>

我可以使用ajax，但我不知道如何在填写的Yii表格中暗示这一点。

在视图中放入以下代码：

<?php
$this->registerJs("$('#rate, #amount').keyup(function(){
        var rate = $('#rate').val(),
            amount = $('#amount').val(),
            fee = 0;
        rate = rate - 0;//convert to integer
        amount = amount - 0;//convert to integer
        fee = rate * amount;
        $('#fee').val(fee);
});"); 
?>

形式：

<div class="loanr" id="loan-rate"><?= $form->field($model, 'amount')->textInput(['id' => 'amount'])?></div>
<div class="loanr" id="loan-rate"><?= $form->field($model, 'fee-rate')->textInput(['id' => 'rate'])?></div>
<div class="loanr" id="loan-fee"><?= $form->field($model, 'fee')->textInput(['id' => 'fee'])?></div>