(function() {
 // 代码
 // ...
})();

function f1()
{
 var N = 0; // N是f1函数的局部变量
 function f2() // f2是f1函数的内部函数，是闭包
 {
 N += 1; // 内部函数f2中使用了外部函数f1中的变量N
 console.log(N);
 }
 return f2;
}
var result = f1();
result(); // 输出1
result(); // 输出2
result(); // 输出3

function Product() {
 var name;
 this.setName = function(value) {
 name = value;
 };
 this.getName = function() {
 return name;
 };
}
var p = new Product();
p.setName("Fundebug");
console.log(p.name); // 输出undefined
console.log(p.getName()); // 输出Fundebug

function Rectangle(x, y)
{
 this._length = x;
 this._breadth = y;
}
Rectangle.prototype.getDimensions = function()
{
 return {
 length: this._length,
 breadth: this._breadth
 };
};
var x = new Rectangle(3, 4);
var y = new Rectangle(4, 3);
console.log(x.getDimensions()); // { length: 3, breadth: 4 }
console.log(y.getDimensions()); // { length: 4, breadth: 3 }

var module = (function() {
 var N = 5;
 function print(x) {
 console.log("The result is: " + x);
 }
 function add(a) {
 var x = a + N;
 print(x);
 }
 return {
 description: "This is description",
 add: add
 };
})();
console.log(module.description); // 输出"this is description" 
module.add(5); // 输出“The result is: 10”

console.log(y); // 输出undefined
y = 2; // 初始化y

var y; // 声明y
console.log(y); // 输出undefined
y = 2; // 初始化y

var add = function(x) {
 return function(y) {
 return x + y;
 };
};
console.log(add(1)(1)); // 输出2
var add1 = add(1);
console.log(add1(1)); // 输出2
var add10 = add(10);
console.log(add10(1)); // 输出11

var user = {
 name: "Rahul Mhatre",
 whatIsYourName: function() {
 console.log(this.name);
 }
};
user.whatIsYourName(); // 输出"Rahul Mhatre",
var user2 = {
 name: "Neha Sampat"
};
user.whatIsYourName.call(user2); // 输出"Neha Sampat"

apply(thisArg, [argsArray])
call(thisArg, arg1, arg2, …)
var user = {
 greet: "Hello!",
 greetUser: function(userName) {
 console.log(this.greet + " " + userName);
 }
};
var greet1 = {
 greet: "Hola"
};
user.greetUser.call(greet1, "Rahul"); // 输出"Hola Rahul"
user.greetUser.apply(greet1, ["Rahul"]); // 输出"Hola Rahul"

var user = {
 greet: "Hello!",
 greetUser: function(userName) {
 console.log(this.greet + " " + userName);
 }
};
var greetHola = user.greetUser.bind({greet: "Hola"});
var greetBonjour = user.greetUser.bind({greet: "Bonjour"});
greetHola("Rahul") // 输出"Hola Rahul"
greetBonjour("Rahul") // 输出"Bonjour Rahul"

function memoizeFunction(func)
{
 var cache = {};
 return function()
 {
 var key = arguments[0];
 if (cache[key])
 {
  return cache[key];
 }
 else
 {
  var val = func.apply(this, arguments);
  cache[key] = val;
  return val;
 }
 };
}
var fibonacci = memoizeFunction(function(n)
{
 return (n === 0 || n === 1) ? n : fibonacci(n - 1) + fibonacci(n - 2);
});
console.log(fibonacci(100)); // 输出354224848179262000000
console.log(fibonacci(100)); // 输出354224848179262000000

function addMethod(object, name, f)
{　　
 var old = object[name];　　
 object[name] = function()
 {
 // f.length为函数定义时的参数个数
 // arguments.length为函数调用时的参数个数　　　　
 if (f.length === arguments.length)
 {　　
  return f.apply(this, arguments);　　　　
 }
 else if (typeof old === "function")
 {
  return old.apply(this, arguments);　　　　
 }　　
 };
}
// 不传参数时，返回所有name
function find0()
{　　
 return this.names;
}
// 传一个参数时，返回firstName匹配的name
function find1(firstName)
{　　
 var result = [];　　
 for (var i = 0; i < this.names.length; i++)
 {　　　　
 if (this.names[i].indexOf(firstName) === 0)
 {　　　　　　
  result.push(this.names[i]);　　　　
 }　　
 }　　
 return result;
}
// 传两个参数时，返回firstName和lastName都匹配的name
function find2(firstName, lastName)
{　
 var result = [];　　
 for (var i = 0; i < this.names.length; i++)
 {　　　　
 if (this.names[i] === (firstName + " " + lastName))
 {　　　　　　
  result.push(this.names[i]);　　　　
 }　　
 }　　
 return result;
}
var people = {　　
 names: ["Dean Edwards", "Alex Russell", "Dean Tom"]
};
addMethod(people, "find", find0);
addMethod(people, "find", find1);
addMethod(people, "find", find2);
console.log(people.find()); // 输出["Dean Edwards", "Alex Russell", "Dean Tom"]
console.log(people.find("Dean")); // 输出["Dean Edwards", "Dean Tom"]
console.log(people.find("Dean", "Edwards")); // 输出["Dean Edwards"]