Javascript MVC Syntax

Question

I saw a Javascript MVC article here, and the model is defined as:

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});
    }

};

question 1. In Javascript, what does underscore means? e.g. this._items

question 2. in model, where does it use, how to use the following things:

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

Caleb · Accepted Answer · 2011-04-13 09:19:36Z

7

The underscore is just convention, it only has meaning to indicate what was in somebodies head when they wrote it. In general people use an underscore to prefix method names that are meant to be private methods, meaning only use internally to a class, not used by other users.

answered Apr 13, 2011 at 9:19

Caleb

5,5272 gold badges51 silver badges70 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

TJHeuvel · Accepted Answer · 2011-04-13 09:20:15Z

1

The underscore doesnt mean anything, you can just use it in your variable names.

In this case it seems to be an indication that its supposed to be used for a private variable.

answered Apr 13, 2011 at 9:20

TJHeuvel

12.6k4 gold badges40 silver badges46 bronze badges

Collectives™ on Stack Overflow

Javascript MVC Syntax

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related