Object-oriented JavaScript learning

Object-oriented

JavaScript inheritance mechanism

Code example:

<script>
         //prototype
         function Person(name ,age){
    
    
            this.name = name;
            this.age = age;
            this.info = function (){
    
    
                document.write("姓名："+this.name+"<br>");
                document.write("年龄："+this.age+"<br>");
            }
        }
        var p1 = new Person("法外狂徒张三",29);
        p1.info();
        Person.prototype.walk = function(){
    
    
            document.write(this.name+"溜达"+"<br>");
        }
        document.writeln("<hr>");
        var  p2 = new Person("leegang" , 30);
        p2.info();
        document.writeln("<hr>");
        p2.walk();
        p1.walk();
     </script>

Constructor implements pseudo-inheritance

Use apply or call to implement pseudo inheritance

Code example:

<script>
        //prototype
        function Person(name ,age){
    
    
           this.name = name;
           this.age = age;
           
       }
       Person.prototype.sayHello = function(){
    
    
             console.log(this.name+"正在打招呼");
       }
       var p1 = new Person("法外狂徒张三",29);
       p1.sayHello();
       function student(name,age,grade){
    
    
           Person.call(this,name,age);
           this.grade = grade;
       }
       student.prototype = new Person();
       student.prototype.intro = function(){
    
    
           console.log("%s是个学生，读%d年级",this.name,this.grade);
       }
       var stu = new student('李四',34,5);
       var stu2 = new student('王五',33,4);
       console.log(stu instanceof student);
       console.log(stu instanceof Person);
       stu.intro();
       stu2.intro();
       stu.sayHello();
       stu2.sayHello();
    </script>

Use the call method to inherit the construction method, and use the prototype property to inherit other methods of the class.
Examples of inherited code:

script>
        function Animal (sex,age){
    
    
            this.sex = sex;
            this.age = age;
        }
        Animal.prototype.intro = function(){
    
    
            console.log("性别："+this.sex+",年龄："+this.age);
        }
        function Dog(kind,sex,age){
    
    
            this.kind = kind;
            Animal.call(this,sex,age);
        }
        Dog.prototype = new Animal();
        Dog.prototype.voice = function (){
    
    
            console.log(this.kind+"叫的声音是：汪汪汪");
        }
        function Cat(kind,sex,age){
    
    
            this.kind = kind;
            Animal.call(this,sex,age);
        }
        Cat.prototype = new Animal();
        Cat.prototype.voice = function (){
    
    
            console.log(this.kind+"叫的声音是：嗷嗷嗷");
        }
        var d = new Dog("哈士奇","公",12);
        d.intro();
        d.voice();
        var c = new Cat("波斯猫","母",5);
        c.intro();
        c.voice();
    </script>

Create object