Question

我试着编写一个函数，1.将一个项添加到一个可观察数组中; 2.如果该项已经存在于数组中，则替换该项

self.addNotification = function (name, availability, note) {
    //see if we already have a line for this product
    var matchingItem = self.notifications.indexOf(name);

    if (matchingItem !== undefined) {
        self.notifications.replace(self.notifications()[index(matchingItem)],
            new Notification(self, name, availability, note));
    }
    else {
        self.notifications.push(new Notification(self, name, availability, note));
    }
};

我做错了什么？

问候安德斯

Answer 1

好吧，Array.prototype.indexOf永远不会返回undefined。它的数字索引为-1（ not found ）或以0开头的任何数字。

Answer 2

以下是我的回答：fiddle

在Chrome中点击F12或在FireFox中使用FireBug查看控制台日志输出。

var notifications = {
    notifs: [],
    updateNotifications: function(notification) {
        'use strict';

        var matchIndex;

        for (matchIndex = 0; matchIndex < this.notifs.length; matchIndex += 1) {
            if (this.notifs[matchIndex].name === notification.name) {
                break;
            }
        }
        if (matchIndex < this.notifs.length) {
            this.notifs.splice(matchIndex, 1, notification);
        } else {
            this.notifs.push(notification);
        }
    }
};

notifications.updateNotifications({
    name: 'John',
    available: false,
    note: "Huzzah!"
});
notifications.updateNotifications({
    name: 'Jane',
    available: true,
    note: "Shazam!"
});
notifications.updateNotifications({
    name: 'Jack',
    available: true,
    note: "Bonzai!"
});
notifications.updateNotifications({
    name: 'Jane',
    available: false,
    note: "Redone!"
});
console.log(notifications);

用于添加和替换可观察数组中的项的函数

2 个答案: