如何创建，分配和访问对象的新值？

Question

How to create, assign and access new values to object ?

Declaring new objects and adding new values to is is problem for me.

can any one help me?

 var Countries = [ 
    {
        name : 'USA',
        states : [
            {
                name : 'NH',
                cities : [
                    {
                        name : 'Concord',
                        population : 12345
                    },
                    {
                        name : "Foo",
                        population : 456
                    }
                    /* etc .. */
                ]
            }
        ]
    },
    {
        name : 'UK',
        states : [ /* etc... */ ]
    }
]

Tried like this:

Countries = new Array();
Countries[0] = new Country("USA");
Countries[0].states[0] = new State("NH");
Countries[0].states[0].cities[0] = new city("Concord",12345);
Countries[0].states[0].cities[1] = new city("Foo", 456);
...
Countries[3].states[6].cities[35] = new city("blah", 345);

Answer 1

You're trying to create new objects over and over with things like new Country and new State but you don't have those defined as functions. Something much more simple should work:

Countries[0].states[0].name = "Not New Hampshire";
console.log(Countries[0].states[0].name);

[Edit] : I also highly agree with upsidedown. Please check a tutorial on working with data structures (arrays and objects) in JavaScript.

Answer 2

As @uʍop-ǝpısdn commented, you'll find lots of tutorials.

One of the common pattern for creating "newable" objects in JavaScript goes like this:

var Country = function(name, states){
    this.name = name;
    this.states = states || [];
}

var State = function(name, cities){
    this.name = name;
    this.cities = cities || [];
}

var Countries = [];
Countries.push( new Country("USA", [ new State("NH", ...), ... ]) );