Javascript MVC和语法问题

Question

我在这里看到了一个javascript MVC文章,模型定义为:

var ListModel = function (items) {
    this._items = items;
    this._selectedIndex = -1;

    this.itemAdded = new Event(this);
    this.itemRemoved = new Event(this);
    this.selectedIndexChanged = new Event(this);
};

ListModel.prototype = {

    getItems : function () {
        return [].concat(this._items);
    },

    addItem : function (item) {
        this._items.push(item);
        this.itemAdded.notify({item: item});
    },

    removeItemAt : function (index) {
        var item = this._items[index];
        this._items.splice(index, 1);
        this.itemRemoved.notify({item: item});
        if (index == this._selectedIndex)
            this.setSelectedIndex(-1);
    },

    getSelectedIndex : function () {
        return this._selectedIndex;
    },

    setSelectedIndex : function (index) {
        var previousIndex = this._selectedIndex;
        this._selectedIndex = index;
        this.selectedIndexChanged.notify({previous: previousIndex});
    }

};  

问题1.在javascript中,下划线意味着什么？例如this._items

问题2.在模型中,它在哪里使用,如何使用以下内容:

this.itemAdded = new Event(this);
    this.itemRemoved = new Event(this);
    this.selectedIndexChanged = new Event(this);

Answer 1

下划线只是惯例,它只是意味着在他们写作时指出某些人的头脑.通常,人们使用下划线来为方法名称添加前缀,这些方法名称是私有方法,这意味着仅在内部使用类,而不是其他用户使用.