ts笔记

1.array tuple，元组为给定数据类型的数组

let arrOfNumbers: number[] = [1,2,3]
let user: [string, number] = ['s', 2]

2.尽量避免用any，因为就失去了ts的意义了

3.Partial，变为可选。 Omit，去掉某个属性。

interface Person {
    name: string
    age: number
}

let viking : Person = { name: 'd', age: 2}
type IPartials = Partial<Person>
let viking2: IPartials = {}

type IOmit = Omit<Person, 'name'>
let viking3: IOmit = {age:1}

4.enum

const enum Direction {
    Up = 10,
    Down,
    Left,
    Right
}

console.log(Direction.Up)

5.interface

interface Person {
    readonly id: number;
    name: string;
    age?: number;
}

let viking: Person = {
    id: 1,
    name: 'dd',
    age: 1,
}

6.范型，对于未知数据来源的一个占位

interface KeyPair<T,U>{
    key: T,
    value: U
}

let kp1: KeyPair<number, string> = {key:1 , value: 'string'}
let kp2: KeyPair<string, number> = {key:'1' , value: 1}

7.type和interface的区别

联合类型只能用type 

type str = string | number

interface可以合并同名接口， type不行

interface A{name:string}
interface A{age:number}
var x:A={name:'xx',age:20}

interface继承用extends，type用&