function N() {}
N.prototype = {}
var n1 = new N();
var n2 = new N();
alert(n1.prototype === n2.prototype);
alert(n1.prototype === N.prototype);
N.prototype = {}
var n1 = new N();
var n2 = new N();
alert(n1.prototype === n2.prototype);
alert(n1.prototype === N.prototype);
var n1 = new N();
var n2 = new N();
//n1 n2在使用了new生成的新对象都是object类型,并没有prototype属性。
alert(n1.prototype === n2.prototype);//true, n1.prototype === undefined,n2.prototype === undefined; undefined === undefined;
alert(n1.prototype === N.prototype); //false, n1.prototype === undefined,N.prototype === object; undefined !== object;//N为function类型,prototype是function的原型链,经常被用来模拟继承。
//function类型的对象,默认的prototype都为object
//所以楼主的 N.prototype = {} 这句代码并无实际意义。