Javascript 为ng类应用不同的表达式

您好，我正在尝试根据此变量的值更改按钮的颜色：$scope.order.orderwindow.invoicedata

我正在更改ng类中的表达式以执行此操作。然而，尽管我的手表有功能，但现在它并没有改变

指令.js

 .directive('invoicetypewatch', function() {
      return {
        restrict: 'A',
        link: function(scope, element, attrs) {
    // change styling of button depending on if id is null or not

    scope.$watch('order.orderwindow.invoicedata', function() {

      if(scope.order.orderwindow.invoicedata.id!=null) {       
    scope.invoice_delete_type_button_styling={"btn btn-danger btn-block":true};

        }else{
        scope.invoice_delete_type_button_styling={"btn btn-danger btn-block":false};
        }
      });

    }
    };
    })

view.html

 <div class="col-lg-4" invoicetypewatch>
<button ng-class="{{invoice_delete_type_button_styling}}" ng-click="delete(invoice_delete_type_button,order.orderwindow.invoicedata.id)">{{invoice_delete_type_button}}</button>
</div>

{{发票\删除\类型\按钮}

我无法测试代码，因为我不知道如何更改

order.orderwindow.invoicedata

，但我的建议是完全删除

监视

，并将视图更改为：

<div class="col-lg-4" invoicetypewatch>
<button ng-class="{'btn btn-danger btn-block':(scope.order.orderwindow.invoicedata.id!=null)}"
  ng-click="delete(invoice_delete_type_button,order.orderwindow.invoicedata.id)"> {{invoice_delete_type_button}}</button>
</div>

{{发票\删除\类型\按钮}

---

这可能有效，但仍取决于

order.orderwindow.invoicedata

的更改方式。确保更改发生在angular应用程序内部，并开始一个新的摘要循环。

我认为您只需在指令中指定类-无需映射对象：

    if(scope.order.orderwindow.invoicedata.id!=null) {       
       scope.invoice_delete_type_button_styling="btn btn-danger btn-block";

    }else{
         scope.invoice_delete_type_button_styling="btn btn-success";
    }

然后只需在ng类中使用该范围变量，而不使用{{}，因为ng类对传入的内容求值

  <button ng-class="invoice_delete_type_button_styling"

 <button class="{{invoice_delete_type_button_styling}}"