Question

我正在尝试将dropdown与可观察数组绑定，并根据条件设置所选项，但所选值未更新。

相同的代码是：

function Item(id, name) {
this.id = ko.observable(id);
this.name = ko.observable(name);
}

var viewModel = function(){
var self= this;
self.test = ko.observable('a'),
self.selectedItem = ko.computed(function () {
    var tempreview = self.test();        
    if (tempreview === "a") {
        return ko.observable("2");
    }
    else
        return ko.observable("3");

}),
self.items = ko.observableArray([new Item(3, "")])
};

var vm = new viewModel();
vm.items([new Item(1, "pencil"),
    new Item(2, "pen"),
    new Item(3, "marker"),
    new Item(4, "crayon")
]);
ko.applyBindings(vm);


<select data-bind="options: items, optionsText: 'name', optionsValue: 'id', value:selectedItem"></select>

<div data-bind="text: selectedItem"></div>

Jsfiddle链接是：//jsfiddle.net/sajesh1985/c7MCh/2 /

谢谢， Sajesh

Answer 1

在selectedItem计算中，只需返回＆＃39; 2＆＃39;或者＆＃39; 3＆＃39;，而不是可观察的：

self.selectedItem = ko.computed(function () {
    var tempreview = self.test();        
    if (tempreview === "a") {
        return '2';
    }
    else
        return '3'

}),

根据knockout.js中的条件设置下拉默认值

1 个答案: