1、立即调用的函数表达式：

	1>      window 作用域中声明变量
		var type = "Red",attack = function() {
			console.log( type + " Bird Attacks!" );
	      };
		console.log( window.type );   // I'm a global variable
		console.log( window.attack ); // I'm a global function
	2>	任何作用于未声明的对象
		var type = "Red",
		attack = function() {
			typeOfBird = type + " Bird";
			return typeOfBird + " Bird Attacks!";
		};
		console.log( window.type );       // I'm a global variable
		console.log( window.attack() );     // I'm a global function
		console.log( window.typeOfBird ); // I'm a global variable too :(
		-- JavaScript 会将忘记声明的变量（上typeOfBird）定义为全局变量
	3>	明确向Window添加对象.
		var type = "Red",
		attack = function() {
			typeOfBird = type + " Bird";
			window.message = typeOfBird + " Attacks!";
			return typeOfBird + " Bird Attacks!";
		};
		console.log( window.type );       // I'm a global variable
		console.log( window.attack() );     // I'm a global function
		console.log( window.typeOfBird ); // I'm a global variable too :(
		console.log( window.message );    // I'm a global variable too :|
	4>	为什么全局变量是个问题。
    	         1、与你项目通组成员代码冲突。
      	         2、与第三方库发生冲突。
       	         3、与浏览器发生冲突。
    	5>	保护自己的多种方式.
	

               1>、对象字面量
			// Gather type & attack and make properties off higher level object
			var bird = {
				type: "Red",
				attack: function() {
					console.log( this.type + " Bird Attacks!" );
				}
			};
			console.log( window.bird );          // Only 1 global object!
			console.log( window.bird.type );     // Red
			console.log( window.bird.attack() ); // Red Bird Attacks! 
		2>、立即调用的函数表达式 IIFE Immediately-invoked Function Expression
			(function(){
			}());
			--------------------------------------
			// Revealing Module Pattern
			var bird = (function() {
				var type = "Red",
					power = "IIFE", // This is private
					attack = function() {
						console.log( type + " Bird Attacks with an " + power +  "!" );
					};
				return { // Only the items returned are public
						type: type,
						attack: attack
				};
			}());
			console.log( window.bird );          // Only 1 global object!
			console.log( window.bird.type );     // Public property
			console.log( window.bird.attack() ); // Public method accessing private var
			console.log( window.bird.power );    // Private variable, can't access 
			---------------------------------------
			(function( bird ) {
				var power = "IIFE"; // This is private
				bird.type = "Red";
				bird.attack = function() {
					console.log( bird.type + " Bird Attacks with an " + power + "!" );
				};
			}( window.bird = window.bird || {} ));
			console.log( window.bird );          // Only 1 global object!
			console.log( window.bird.type );     // Public property
			console.log( window.bird.attack() ); // Public method accessing private var
			console.log( window.bird.power );    // Private variable, can't access