var student={};
console.log(student);//Object{}
student.name='xiaoming';
student.age=12;
console.log(student);//Object{name:'xiaoming',age:'12'}
//删除操作
for(var key in student){
    delete student[key];
}
console.log(student);//Object{}

var student={};
console.log(student);//Object{}
student.name='xiaoming';
student.age=12;
console.log(student);//Object{name:'xiaoming',age:'12'}
//删除操作
for(var key in student){
    delete student[key];
}
console.log(student);//Object{}