function fun(){this.name = "mm";}var obj = new fun();console.log(obj.name);//mmdelete obj.name;console.log(obj.name); //undefined2,变量删除var name = "lily";delete name;console.log(name); //lily直接用delelte删除不了变量
fun.prototype.age = 18;delete obj.age;console.log(obj.age) //18