TS笔记

• 公式： 变量名：类型 = 赋值
• 联合类型（或的关系）
• 缺点：返回值提示类型很模糊

function reverse_union(x:string | number):string|number|void{
}

• 函数重载

function reverse(x:number):number{}
function reverse(x:string):string{}
function reverse(x:string | number):string|number|void{}

• 可索引接口

interface RandomKeyArr{
    [propName: number]:string
}
const obj3:RandomKeyArr = ['1','2']

interface RandomIntroduce{
    name:string,
    age:number,
    [propName:string]:string | number | undefined
}
const randomPerson:RandomIntroduce = {
    name:'wang',
    age:23,
    like:'swim',
    cook:'good'
}

• 类实现接口

interface IWake{
    wakeUp():void
}
interface IMusic{
    playMusic():void
}
//类实现接口
class Alarm implements IWake,IMusic{
    wakeUp():void{
    }
    playMusic():void{}
}

• 接口继承接口，好处：代码复用,接口可以随意组合

interface ISmartAudio extends IWake,IMusic{
    controlSomething():void
}
class Smart implements ISmartAudio{
    controlSomething():void{}
     wakeUp():void{
    }
    playMusic():void{}
}
    

• 抽象类和接口的区别
  • 抽象类：类是单一继承
  • 类可以实现多个接口
• 泛型：使用时才能确定类型

function printT<T>(arg:T):T{
}
printT<number>(123)

 泛型约束接口

interface ILength{
    length:number
}
function logLength<T extends ILength>(arg:T):T{
}