面向对象--(继承)

实现继承的关键在于：子类必须拥有父类的全部属性和方法，同时子类还应该能定义自己特有的属性和方法

父类：

function People(name,age,sex){
				this.name=name;
				this.age=age;
				this.sex=sex;
			}
			People.prototype.sayHello=function(){
				console.log('你好，我是'+this.name+'我今年'+this.age+'岁了')
			}
			People.prototype.sleep=function(){
				console.log(this.name+'开始睡觉~~~')
			}

子类：

function Student(name,age,sex,school,studentNumber){
				this.name=name;
				this.age=age;
				this.sex=sex;
				this.school=school;
				this.studentNumber=studentNumber
			}
			
			//关键语句，实现继承
			Student.prototype=new People();
			
			Student.prototype.study=function(){
				console.log(this.name+'正在学习')
			}
			Student.prototype.exam=function(){
				console.log(this.name+'正在考试，加油')
			}
			
			//实例化
			var hanmeimei=new Student('韩梅梅',9,'女','清华小学','100556')
			hanmeimei.study()
			hanmeimei.sayHello()