javascript - 过滤器与 knockout.js 绑定(bind)的问题

Question

我是新使用 Knockout.js 框架的人，我的代码中出现以下错误，我正在使用 Knockout.js 构建应用程序，一切正常，除了当我尝试创建 dependentObservable 时。

这是 JavaScript 代码:

(function() {
  'use strict';

    console.log("This is my Application");

     var app = {
         mapElement: document.getElementById('map'),
         mapObj: map,
         locations : ko.observableArray([
            {id: 1, title: 'Holywood Theater', location: {lat: 43.098344, lng: -76.145697}},
            {id: 2, title: 'Mattydale Fire Department', location: {lat: 43.098172, lng: -76.142189}},
            {id: 3, title: 'Original Italian Pizza', location: {lat: 43.098854, lng:  -76.144700}},
            {id: 4, title: 'Roxboro Road Middle School', location: {lat: 43.101110, lng: -76.150901}},
            {id: 5, title: 'Big Lots', location: {lat: 43.101400, lng: -76.146985}},
            {id: 6, title: 'Camnel pub', location: {lat: 43.098670, lng: -76.145832}}
        ]),
        markers:[],
        textFilter: ko.observable(),
        filterLocations: ko.dependentObservable(function () {
                            return ko.utils.arrayFilter(app.locations(), function (loc) {
                                return loc.title().toLowerCase().includes(app.textFilter().toLowerCase());
                            });
                        })
     };

    ko.applyBindings(app);
})();

chrome控制台的错误是:

Uncaught TypeError: Cannot read property 'locations' of undefined

Answer 1

您不能使用“app”var，因为您仍在创建它。

var app = {... 

    ^^^    return ko.utils.arrayFilter(app.locations(), ...

                                       ^^^