|
| 1 | +--- |
| 2 | +title: 接口 |
| 3 | +order: 6 |
| 4 | +toc: menu |
| 5 | +nav: |
| 6 | + title: TypeScript |
| 7 | +--- |
| 8 | + |
| 9 | +## 概述 |
| 10 | + |
| 11 | +- 接口的含义:在面向对象编程中表示行为的抽象,或者描述对象的形状 |
| 12 | +- 接口的作用:为这些类型命名和为你的代码或第三方代码定义契约 |
| 13 | + |
| 14 | +## 基本使用 |
| 15 | + |
| 16 | +```javascript |
| 17 | +namespace d { |
| 18 | + interface IUser { |
| 19 | + username: string; |
| 20 | + age: number; |
| 21 | + } |
| 22 | + |
| 23 | + const getUserName = (user: IUser) => user.username; |
| 24 | + |
| 25 | + getUserName({ username: 'rain', age: 12 }); |
| 26 | +} |
| 27 | +``` |
| 28 | + |
| 29 | +## 支持任意参数 |
| 30 | + |
| 31 | +```javascript |
| 32 | +namespace d { |
| 33 | + interface IUser { |
| 34 | + username: string; |
| 35 | + age: number; |
| 36 | + [key: string]: any; |
| 37 | + } |
| 38 | + |
| 39 | + const getUserName = (user: IUser) => user.username; |
| 40 | + |
| 41 | + getUserName({ username: 'rain', age: 12, sex: 'male' }); |
| 42 | +} |
| 43 | + |
| 44 | +``` |
| 45 | + |
| 46 | +## 接口继承接口 |
| 47 | + |
| 48 | +```javascript |
| 49 | +interface IUser { |
| 50 | + name: string; |
| 51 | + age: number; |
| 52 | +} |
| 53 | + |
| 54 | +interface IExtendUser extends IUser { |
| 55 | + sex: string; |
| 56 | +} |
| 57 | +``` |
| 58 | + |
| 59 | +## 类继承多个接口 |
| 60 | + |
| 61 | +```javascript |
| 62 | +namespace d { |
| 63 | + // 接口中的内容是抽象的,没有具体实现 |
| 64 | + interface IUser { |
| 65 | + speak(name: string): void; // 描述类的原型方法时,如果为void代表不关心方法的返回值 |
| 66 | + count: number; |
| 67 | + } |
| 68 | + |
| 69 | + interface IHome { |
| 70 | + adress: string; |
| 71 | + } |
| 72 | + |
| 73 | + class User implements IUser, IHome { |
| 74 | + speak(name: string): string { |
| 75 | + return 'rain'; |
| 76 | + } |
| 77 | + public count!: number; |
| 78 | + adress!: string; |
| 79 | + } |
| 80 | +} |
| 81 | + |
| 82 | +``` |
| 83 | + |
| 84 | +## `type`和`interface`区别 |
| 85 | + |
| 86 | +- 相同点: |
| 87 | + |
| 88 | + - 都可以描述一个对象或者函数 |
| 89 | + |
| 90 | + ```javascript |
| 91 | + // interface |
| 92 | + interface IUser { |
| 93 | + name: string; |
| 94 | + age: number; |
| 95 | + } |
| 96 | + |
| 97 | + interface ISetUser { |
| 98 | + (name: string, age: number): void; |
| 99 | + } |
| 100 | + |
| 101 | + // type |
| 102 | + type myUser = { |
| 103 | + name: string, |
| 104 | + age: string, |
| 105 | + }; |
| 106 | + |
| 107 | + type setMyUser = (name: string, age: number) => void; |
| 108 | + ``` |
| 109 | + |
| 110 | + - 拓展(extends)与 交叉类型(Intersection Types) |
| 111 | + |
| 112 | + ```javascript |
| 113 | + // interface可以extends,但type是不允许extends和implement的 |
| 114 | + // type可以通过交叉类型实现interface的extend行为 |
| 115 | + // 两者不是相互独立的,interface可以继承type,type也可以与nterface类型交叉 |
| 116 | + |
| 117 | + // interface extends interface |
| 118 | + interface IName { |
| 119 | + name: string; |
| 120 | + } |
| 121 | + interface IUser extends IName { |
| 122 | + age: number; |
| 123 | + } |
| 124 | + // type 与 type 交叉 |
| 125 | + type myName = { |
| 126 | + name: string, |
| 127 | + }; |
| 128 | + type myUser = myName & { age: number }; |
| 129 | + |
| 130 | + // interface extends type |
| 131 | + interface IExtend extends myName { |
| 132 | + age: number; |
| 133 | + } |
| 134 | + // type 与 interface 交叉 |
| 135 | + type User = IName & { |
| 136 | + age: number, |
| 137 | + }; |
| 138 | + ``` |
| 139 | + |
| 140 | +- 不同点: |
| 141 | + |
| 142 | + - type 可以声明基本类型别名,联合类型,元组等类型 |
| 143 | + |
| 144 | + ```javascript |
| 145 | + // 基本类型别名 |
| 146 | + type Name = string |
| 147 | + |
| 148 | + // 联合类型 |
| 149 | + interface Dog { |
| 150 | + wong(); |
| 151 | + } |
| 152 | + interface Cat { |
| 153 | + miao(); |
| 154 | + } |
| 155 | + |
| 156 | + type Pet = Dog | Cat |
| 157 | + |
| 158 | + // 具体定义数组每个位置的类型 |
| 159 | + type PetList = [Dog, Pet] |
| 160 | + ``` |
| 161 | + |
| 162 | + - `type`语句中还可以使用`typeof`获取实例的类型进行赋值 |
| 163 | + ```javascript |
| 164 | + // 当你想获取一个变量的类型时,使用 typeof |
| 165 | + let div = document.createElement('div'); |
| 166 | + type B = typeof div; |
| 167 | + ``` |
| 168 | + - `interface`可以声明合并 |
| 169 | + |
| 170 | + ```javascript |
| 171 | + interface User { |
| 172 | + name: string |
| 173 | + age: number |
| 174 | + } |
| 175 | +
|
| 176 | + interface User { |
| 177 | + sex: string |
| 178 | + } |
| 179 | +
|
| 180 | + /* |
| 181 | + User 接口为 { |
| 182 | + name: string |
| 183 | + age: number |
| 184 | + sex: string |
| 185 | + } |
| 186 | + */ |
| 187 | + ``` |
| 188 | + |
| 189 | + **type 关键字的产生的东西官方有一个名字 type aliases ,就是类型别名,重点是它是别名不是真正的类型** |
| 190 | + |
| 191 | + 更多内容参考:https://github.com/SunshowerC/blog/issues/7 |
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