在knockout js中的bindingcontext中为属性赋值

Question

我想动态地为bindingContext中的属性赋值。

 ko.bindingHandlers.dropdown =
 {
    update: function (element, valueAccessor, allBindingsAccessor, bindingContext) {
        var param = allBindingsAccessor().dropdownOptions;
        $(element).change(function () {

           //bindingContext[param.Text]= value;
        });
     }
}