var o = new Object();
                o.a = "A";
                o.b = "B";
                o.c = "C";
                alert(o.a + o.b + o.c);

var o1 = {a:1, b:2, c:3};
                alert(o1.a + o1.b + o1.c);

var o = new Object();
                o.a = "A";
                o.b = "B";
                o.c = "C";
                o.d = {x:1, y:2, z:3};
                alert(o.a + o.b + o.c + o.d.x + o.d.y + o.d.z);

var o = new Object();
                o.a = "A";
                o.b = "B";
                o.c = "C";
                o.d = {x:1, y:2, z:3};
                o.a = o.no_such_property;
                delete o.b;
                o.c = null;
                o.d.x = void 0;
                alert(o.a + ',' + o.b + ',' + o.c + ',' + o.d.x + ',' + o.d.y + o.d.z);

var o = new Object();
                o.a = "A";
                o.b = "B";
                o.c = "C";
                o.d = {x:1, y:2, z:3};
                var s = "";
                for (i in o)
                {
                    s += i + ",";
                }
                alert(s);

function init()
            {
                function Book(name, author)
                {
                    this.name = name;
                    this.author = author;
                }
                var book1 = new Book('The Republic', 'Plato');
                var book2 = new Book('A History of Western Philosophy', 'Russel');
                alert("<" + book1.name + ">(" + book1.author + ")");
                alert("<" + book2.name + ">(" + book2.author + ")");
            }

<The Republic>(Plato)

<A History of Western Philosophy>(Russel)

function Book(name, author)
                {
                    this.name = name;
                    this.author = author;
                }
                function toString()
                {
                    return "<" + this.name + ">(" + this.author + ")";
                }
                var book1 = new Book('The Republic', 'Plato');
                book1.toString = toString;
                var book2 = new Book('A History of Western Philosophy', 'Russel');
                book2.toString = toString;
                alert(book1.toString());
                alert(book2.toString());

<A History of Western Philosophy>(Russel)

function Book(name, author)
                {
                    this.name = name;
                    this.author = author;
                    this.toString = toString;
                }
                function toString()
                {
                    return "<" + this.name + ">(" + this.author + ")";
                }
                var book1 = new Book('The Republic', 'Plato');
                var book2 = new Book('A History of Western Philosophy', 'Russel');
                alert(book1.toString());
                alert(book2.toString);

<The Republic>(Plato)

function toString()
                {
                    return "<" + this.name + ">(" + this.author + ")";
                }

function init()
        {
            function Book(title, author)
            {
                this.title = title;
                this.author = author;
            }
            function toString()
            {
                return this.title + "," + this.author + "," + this.subject;
            }
            Book.prototype.subject = "Philosophy";
            Book.prototype.toString = toString;
            var book = new Book("Republic", "Plato");
            document.write(book.toString() + "<br>");
            for (i = 1;i <= 5; i++)
            {
                book = new Book("T" + i, "A" + i)
                if (i % 2 == 0) Book.prototype.subject = "Maths";
                else Book.prototype.subject = "Chemistry";
                document.write(book.toString() + "<br>");
            }
        }

Republic,Plato,Philosophy
T1,A1,Chemistry
T2,A2,Maths
T3,A3,Chemistry
T4,A4,Maths
T5,A5,Chemistry

function init()
        {
            function Book(title, author)
            {
                this.title = title;
                this.author = author;
            }
            function toString()
            {
                var v = "";
                for (s in this)
                {
                    v+= s + ",";
                }
                return v;
            }
            Book.prototype.toString = toString;
            var book = new Book("Republic", "Plato");
            document.write(book.toString() + "<br>");
            Book.prototype.subject = "Philosophy";
            document.write(book.toString() + "<br>");  
        }

title,author,
subject,title,author,

function Book(title, author)
            {
                this.title = title;
                this.author = author;
            }
            function getFields(O)
            {
                var v = "";
                for (s in O)
                {
                    v+= s + "=" + O[s] + ",";
                }
                return v;
            }
            var A = new Book("Ta", "Aa");
            var B = new Book("Tb", "Ab");
            document.write("--------------------------<br>");
            document.write(getFields(A) + "<br>");
            document.write(getFields(B) + "<br>"); 
            B.pages = 508;
            B.price = "$20.50";
            document.write("--------------------------<br>");
            document.write(getFields(A) + "<br>");
            document.write(getFields(B) + "<br>");
            Book.prototype = B;
            document.write("--------------------------<br>");
            document.write(getFields(A) + "<br>");
            document.write(getFields(B) + "<br>"); 
            document.write("--------------------------<br>");
            document.write(getFields(Book.prototype) + "<br>");
            var C = new Book("Tc", "Ac");
            document.write("--------------------------<br>");
            document.write(getFields(C) + "<br>");

--------------------------
title=Ta,author=Aa,
title=Tb,author=Ab,
--------------------------
title=Ta,author=Aa,
title=Tb,author=Ab,pages=508,price=$20.50,
--------------------------
title=Ta,author=Aa,

//在“Book.prototype=B”执行以后，对象A并没有获得B中的两个新属性。奇怪。新创建的对象C却获得了。
title=Tb,author=Ab,pages=508,price=$20.50,
--------------------------
title=Tb,author=Ab,pages=508,price=$20.50,
--------------------------
price=$20.50,pages=508,title=Tc,author=Ac,

function Book(title, author)
            {
                this.title = title; //实例变量
                this.author = author;
            }
            Book.prototype.toString = function() //实例方法
            {
                var a = "Book[";
                for (s in this)
                {
                    a += s + "=" + this[s] + ";";
                }
                a += "]";
                return a;
            }
            Book.toString = function(book) //静态方法
            {
                var a = "Book[";
                for (s in book)
                {
                    a += s + "=" + book[s] + ";";
                }
                a += "]";
                return a;
            }
            var A = new Book("Ta", "Aa");
            Book.KIND = "book"; //静态变量
            document.write(A.KIND + ";" + Book.KIND + "<br>");
            document.write(A.toString() + "<br>");
            document.write(Book.toString(A) + "<br>");