第三章 对象(JavaScript:语言精粹)

// 3.1 code 1
var empty_object = {};

var stooge = {
    "first-name": "Jerome",
    "last-name": "Howard"
};

// 3.1 code 2
var filght = {
    airline: "Oceanic",
    number: 815,
    departure: {
        IATA: "SYD",
        time: "2004-09-22 14:55",
        city: "Sydney"
    },
    arrival: {
        IATA: "LAX",
        time: "2004-09-23 10:42",
        city: "Los Angeles"
    }
}

// 3.2 code 3
stooge["first-name"]  // "Jerome"
flight.departure.IATA // "SYD"

// 3.2 code 4
stooge["middle-name"] // undefined
flight.status         // undefined
stooge["FIRST-NAME"]  // undefined

// 3.2 code 5
var middle = stooge["middle-name"] || "(none)";
var status = flight.status || "unknown";

// 3.2 code 6
flight.equipment                           // undefined
flight.equipment.model                     // throw "TypeError"
flight.equipment || flight.equipment.model // undefined

stooge[‘first-name‘] = "Jerome";
stooge[‘middle-name‘] = "Lester";
flight.equipment = {
    model: "Boeing 777"
};
flight.status = "overdue";

// 3.4 code 8
var x = stooge;
x.nickname = "Curly";
stooge.nickname;            // "Curly"

var a = {}, b = {}, c = {}; // refer the diff Object
a = b = c = {};             // refer the same Object

// 3.5 code 9
if (typeof Object.beget !== ‘function‘) {
    Object.create = function (obj) {
        var Func = function () {};
        Func.prototype = obj;
        return New Func();
    };    
}
var new_stooge = Object.create(stooge);

// 3.5 code 10
new_stooge[‘first-name‘] = ‘Harry‘; 
new_stooge[‘middle-name‘] = ‘Moses‘; 
new_stooge.nickname = ‘Moses‘;    

// 3.5 code 11
stooge.profession = ‘actor‘;
new_stooge.profession // ‘actor‘

// 3.6 code 12
typeof flight.number   // ‘number‘
typeof flight.status   // ‘string‘
typeof flight.arrival  // ‘object‘
typeof flight.manifest // ‘undefined‘

// 3.6 code 13
typeof flight.toString    // ‘function‘
typeof flight.constructor // ‘function‘

// 3.6 code 14
flight.hasOwnProperty(‘number‘)      // true
flight.hasOwnProperty(‘constructor‘) // false

// 3.7 code 15
var name;
for (name in new_stooge) {
    if (typeof new_stooge[name] !== ‘function‘ || !new_stooge.hasOwnProperty(name)) {
        document.writeln(name + ‘: ‘ + new_stooge[name]);
    }
}

// 3.7 code 16
var i;
var properties = [
    ‘first-name‘,
    ‘middle-name‘,
    ‘last-name‘,
    ‘profession‘
];
for (i = 0; i < properties.length; i += 1) {
    document.writeln(properties[i] + ‘: ‘ + new_stooge[properties[i]]);
}

// 3.8 code 17
new_stooge.nickname         // ‘Moe‘ object‘s value
delete new_stooge.nickname;
new_stooge.nickname         // ‘Curly‘ exposed prototype‘s value

// 3.9  code 18
var MYAPP = {};

// 3.9 code 19
MYAPP.stooge = {
    "first-name": "Jerome",
    "last-name": "Howard"
};

MYAPP.filght = {
    airline: "Oceanic",
    number: 815,
    departure: {
        IATA: "SYD",
        time: "2004-09-22 14:55",
        city: "Sydney"
    },
    arrival: {
        IATA: "LAX",
        time: "2004-09-23 10:42",
        city: "Los Angeles"
    }
}