javascript原型继承

Posted 2020-12-04 minjh

用一张图来表示新的原型链：

 

封装一个inherits()函数，函数F用于桥接

function inherits(Child, Parent) {
    var F = function () {};
    F.prototype = Parent.prototype;
    Child.prototype = new F();
    Child.prototype.constructor = Child;
}

这样inherits()函数就可以重复使用了

function Student(props) {
    this.name = props.name || ‘Unnamed‘;
}

Student.prototype.hello = function () {
    alert(‘Hello, ‘ + this.name + ‘!‘);
}

function PrimaryStudent(props) {
    Student.call(this, props);
    this.grade = props.grade || 1;
}

// 实现原型继承链:
inherits(PrimaryStudent, Student);

// 绑定其他方法到PrimaryStudent原型:
PrimaryStudent.prototype.getGrade = function () {
    return this.grade;
};

// 创建xiaoming:
var xiaoming = new PrimaryStudent({
    name: ‘小明‘,
    grade: 2
});
xiaoming.name; // ‘小明‘
xiaoming.grade; // 2

// 验证原型:
xiaoming.__proto__ === PrimaryStudent.prototype; // true
xiaoming.__proto__.__proto__ === Student.prototype; // true

// 验证继承关系:
xiaoming instanceof PrimaryStudent; // true
xiaoming instanceof Student; // true

 

原型继承 - 廖雪峰的官方网站 （选自 @廖雪峰）

https://www.liaoxuefeng.com/wiki/001434446689867b27157e896e74d51a89c25cc8b43bdb3000/0014344997013405abfb7f0e1904a04ba6898a384b1e925000