function fun(){this.name = ‘mm‘;}var obj = new fun();console.log(obj.name);//mmdelete obj.name;console.log(obj.name); //undefined2、变量不能删除var name = ‘lily‘;delete name;console.log(name); //lily 3、删除不了原型链中的变量fun.prototype.age = 18;delete obj.age;console.log(obj.age) //18原文：http://www.cnblogs.com/Yirannnnnn/p/4846407.html