声明对象类型

定义对象的方式要用接口可以理解定义接口来进行数据结构约束

不能多属性不能少属性

tsx

interface Person{
    name:string
    age:number
}
//1.属性不多不少 ok
const person :Person = {
    name:'小明',
    age:18
}
//2.少属性 no
const person1:Person = {
    name:'小刘'
}
//3.多属性 no
const person2:Person={
    name:'小红',
    age:18,
    class:9
}

interface重名属性重合且实例化接口得符合不能多属性和少属性规则

tsx

interface Book {
    name:string
    price:number
 
}
interface Book {
    publish:boolean
}
const book:Book = {
    name:'三国演义',
    price:20,
    publish:true
}//这样是ok

interface接口可选属性使用？操作符可选属性再实例化时可选可不选

tsx

interface Book {
    name:string
    price?:number
}
const book:Book = {
    name:'三国演义'
}

interface接口索引签名**[key:string]:any**
索要签名：允许定义对象可以具有任意数量的属性，这些任意属性的键是字符串值是any
使用了索引签名之后可以在定义变量中添加任意符合索引签名形式的属性
tsx
```
interface Book {
    name:string
    author:string
    [key；string]:any
}
const book:Book = {
    name:'三国演义',
    author:'罗贯中',
    price:18,
    publish:true
}
```

interface接口只读属性 readonly

tsx

interface Book {
    readonly name:string
    price?:number
    [propName:string]:any
}
const book:Book = {
    name:'三国演义',
    author:'罗贯中'
}
book.name = '水浒传'//这样是报错的

interface接口继承实例接口要实现每个接口的属性和方法

tsx

interface A {
    bookName:string
}
interface B extends A{
    author:string
}
const ab:B={
    bookName:'三国演义',
    author:'罗贯中'
}

interface接口定义函数类型

tsx

interface Book{
    readonly name:string
    price?:number
    author:string
    [propName:string]:any
    fn:() => void 
}
const book:Book={
    name:'三国演义',
    author:'罗贯中',
    publish:true,
    fn:()=>{
        console.log('xxx')
    }
}

声明对象类型 ​

声明对象类型