How to use the prototype object

1. Prototype object: When any function is created, the system will automatically create the corresponding object, called the prototype object

2. The role of the prototype object: solve the memory waste of the constructor + variable pollution

3. The relationship between constructors, prototype objects, and instance objects

• prototype: belongs to the constructor, pointing to the prototype object
• * Solve constructor memory waste + variable pollution

• __proto__: belongs to the instance object, pointing to the prototype object
• * Let the instance object directly access the members of the prototype

• constructor: belongs to the prototype object, pointing to the constructor
• * Allows the instance object to know which constructor it was created by

        //1.构造函数
        function createP (name, age, sex) {
            this.name = name
            this.age = age
            this.sex = sex

        }
        //2.原型对象
        console.log(createP.prototype);
        //给原型对象添加方法
        createP.prototype.eat = function () {
            console.log('吃东西')
        }
        createP.prototype.learn = function () {
            console.log('学习')
        }
        //3.实例对象
        let p1 = new createP('张三', 20, '男')
        let p2 = new createP('李四', 22, '男')
        // console.log(p1, p2);
        //实例对象可以直接调用原型对象里的方法
        p1.eat()
        p2.learn()