<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <script> class Father { constructor(x,y) { this.x = x; this.y = y; } sum() { console.log(this.x + this.y) } } class Son extends Father { constructor(x,y) { super(x,y); this.x = x; this.y = y; } substract() { console.log(this.x-this.y) } } var son1 = new Son(5,3) son1.substract() son1.sum() </script> </body> </html>
ES6之前没有类，通过构造函数模拟类
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <script> function Star(uname,age) { this.uname = uname; this.age = age; this.sing = function() { console.log('我会唱歌') } } var ldh = new Star('刘德华',19) var zxy = new Star('张学友',23) console.log(ldh); ldh.sing(); zxy.sing(); </script> </body> </html>
实例成员就是带this的成员，只能通过实例化对象访问
静态成员只能通过构造函数访问
但是构造函数存在浪费内存的问题，所以引入原型对象prototype的概念，实现方法共享
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <script> function Star(uname,age) { this.uname = uname; this.age = age; } } Star.prototype.sing = function() { consloe.log('我会唱歌') } var ldh = new Star('刘德华',19) var zxy = new Star('张学友',23) ldh.sing(); zxy.sing(); </script> </body> </html>
原型链
