function Fn(){}
var obj = new Fn();
console.log( obj.constructor === Fn ); // true  对象的constructor属性描述的就是其构造函数

//利用字符串截取获取
var str = ''+obj.constructor;
var str1 = str.replace('function','|');//先将function字符用 | 代替，方便截取
var startIndex = str1.indexOf('|'); //找到字符串截取开始索引
var endIndex = str1.indexOf('(');  //找到字符串截取结尾索引
if( startIndex != -1 && endIndex != -1 ){var name = str1.slice( startIndex+2,endIndex );console.log(name);
}

//利用正则表达式获取
var reg = /function (.+)\(/;
var name1 = reg.exec(str);
console.log(name1);

//用name属性获取constructor
console.log(obj.constructor.name);//ie8以下不支持

//兼容所有浏览器获得构造函数名称
function getFnName(fn){/*if(typeof fn !== 'function') return;return fn.name ?fn.name:/function (.+)\(/.exec(fn + '')[1];*/  /*if(typeof fn !== 'function') return;return fn.name ||/function (.+)\(/.exec(fn + '')[1];*/return typeof fn !== 'function'?undefined:fn.name ||/function (.+)\(/.exec(fn + '')[1];
}
function PersonWu(){}
var obj2 = new PersonWu();
var name = getFnName(obj2.constructor);
console.log(name);//PersonWu

var string = '123abc456';
var i = 3;
//substring(startIndex,length) == substr  用法相同
console.log(string.substring(0,i));//123  若传两个参数表示从左边开始从索引值0开始提取前i个字符
console.log(string.substring(i));  //456  若传一个参数代表从左边开始第i个截取至最右侧
//slice(startIndex,enIndex)
console.log(string.slice(0,i))  //包左不包右,-1代表右侧第一位
//string.replace(regexp/substr,replacement)

function Construct(){// 确保只有单例，确保只构造一次if( Construct.unique !== undefined ){return Construct.unique; }// 其他代码this.name = "NYF";this.age="24";Construct.unique = this;
}
var t1 = new Construct() ;
var t2 = new Construct() ;
// 那么也有的， t1 === t2 。

var SingleTon = function(name){ //创建一个对象this.name = name;this.instance = null;
};
SingleTon.prototype.getName = function(){alert(this.name);
};
SingleTon.getInstance = function(name){if(!this.instance){this.instance = new SingleTon(name);}return this.instance;
};var a = SingleTon.getInstance( 'instance1' );
var b = SinleTon.getInstance( 'instance2' );alert( a === b);  //返回true

var single = (function(){var unique;function fn(){this.name = '1';}unique =  new fn;return function (){return unique;};
})();
single();

var CreateDiv = function(html){this.html = html;this.init();
};CreateDiv.prototype.init = function(){var div = document.createElement( 'div' );div.innerHTML = this.html;document.body.appendChild( div );
};var ProxySingleTonCreateDiv = (function (){var instance;return function (html){console.log(instance)if(!instance){instance =   new CreateDiv( html );}return instance;}
})();
var t1 = new ProxySingleTonCreateDiv('a');
var t2 = new ProxySingleTonCreateDiv('b');
console.log(t1===t2)