单例模式

var Singleton = (function(){var instance;var init = function(){var privateTest = function(){console.log('i am a instance!');};return {test: privateTest};};return {getInstance: function(){if ( !instance) {instance = init();};return instance;}};})();var s1 = Singleton.getInstance();var s2 = Singleton.getInstance();s1.test();s2.test();console.log(s1 === s2);//反例var Singleton2 = (function(){var instance;var init = function(){var privateTest = function(){console.log('i am a instance!');};return {test: privateTest};};return {getInstance: init};})();var s3 = Singleton2.getInstance();var s4 = Singleton2.getInstance();s3.test();s4.test();console.log(s3 === s4);