var book = {"main title": "JavaScript", // Property names include spaces,'sub-title': "The Definitive Guide", // and hyphens, so use string literals"for": "all audiences", // for is a reserved word, so quoteauthor: { // The value of this property isfirstname: "David", // itself an object. Note thatsurname: "Flanagan" // these property names are unquoted.}
};

var o = new Object(); // Create an empty object: same as {}.
var a = new Array(); // Create an empty array: same as [].
var d = new Date(); // Create a Date object representing the current time
var r = new RegExp("js"); // Create a RegExp object for pattern matching.

var o1 = Object.create({x:1, y:2}); // o1继承了属性x和y.
var o2 = Object.create(null); // o2不继承任何属性和方法，因此不能和"+"运算符一起正常工作
var o3 = Object.create(Object.prototype); // o3和{}或者new Object()一样.

var author = book.author; // Get the "author" property of the book.
var name = author.surname // Get the "surname" property of the author.
var title = book["main title"] // Get the "main title" property of the book.

book.edition = 6; // Create an "edition" property of book.
book["main title"] = "ECMAScript"; // Set the "main title" property.

function addstock(portfolio, stockname, shares) {portfolio[stockname] = shares; // 使用关联数组
}

var unitcircle = { r:1 }; // 供继承的对象
var c = inherit(unitcircle); // c 继承属性 r
c.x = 1; c.y = 1; // c 定义了两个自己的属性
c.r = 2; // c 覆盖其继承的属性
unitcircle.r; // => 1: 原型对象不受影响

book.subtitle; // => undefined: 属性不存在// 抛出一个类型异常错误. undefined没有length属性
var len = book.subtitle.length;// 一种更简练的常用方法，获得subtitle的length属性或undefined
var len = book && book.subtitle && book.subtitle.length;// 内置构造函数的原型是只读的
Object.prototype = 0; // 赋值失败,但没有报错; Object.prototype没有修改

o = {x:1}; // o有一个属性x， 并继承属性toString
delete o.x; // 删除x, 返回true
delete o.x; // 什么都没做(x已经不存在了), 返回true
delete o.toString; // 什么都没做(toString是继承来的), 返回true
delete 1; // 无意义, 返回true

delete Object.prototype; // 不能删除，属性是不可配置的
var x = 1; // 声明一个全局变量
delete this.x; // 不能删除这个属性
function f() {} // 声明一个全局函数
delete this.f; // 也不能删除全局函数

this.x = 1; // 创建一个可配置的全局属性(没有用 var)
delete x; // 将它删除

delete x; // 在严格模式下报语法错误
delete this.x; // 正常工作