TS 函数重载实例DEMO

TS 函数重载实例DEMO

在TS中 , 函数的重载可以脱离类的使用

type MessageType = "image" | "audio" | string;//微信消息类型

type Message = {
  id: number;
  type: MessageType;
  sendmessage: string;
};

let messages: Message[] = [
  //let messages: Array<Message> = [
  {
    id: 1, type: 'image', sendmessage: "你好啊,今晚咱们一起去三里屯吧",
  },
  {
    id: 2, type: 'audio', sendmessage: "朝辞白帝彩云间，千里江陵一日还"
  },
  {
    id: 3, type: 'audio', sendmessage: "你好！张无忌"
  },
  {
    id: 4, type: 'image', sendmessage: "刘老根苦练舞台绝技！"
  },
  {
    id: 5, type: 'image', sendmessage: "今晚王牌对王牌节目咋样?"
  }]

// function getMessage(value: number | MessageType):
//   Message | undefined | Array<Message> {
//   if (typeof value === "number") {
//     return messages.find((msg) => { return value === msg.id })
//   } else {
//     //return messages.filter((msg) => { return value === msg.type })
//     return messages.filter((msg) => value === msg.type)
//   }
// }

function getMessage(value: number, myname: string): Message//第一个根据数字id来查询单个消息的重载签名
function getMessage(value: MessageType, readRecordCount: number): Message[]//第二个根据消息类型来查询消息数组的重载签名
//function getMessage(value: number | MessageType, readRecordCount: number = 1): Message | undefined | Message[] {
//function getMessage(value: any, readRecordCount: any = 1): Message | undefined | Message[] {
//function getMessage(value: any, readRecordCount: any = 1):any {
//function getMessage(value: any, myname: string = "abc", readRecordCount: any = 1) {
function getMessage(value: any, value2: any = 1) {
  //console.log(myname)
  if (typeof value === "number") {
    return messages.find((msg) => { return 6 === msg.id })//undefined
  } else {
    //return messages.filter((msg) => { return value === msg.type })
    return messages.filter((msg) => value === msg.type).splice(0, value2)
  }
}
getMessage(1, "df")
// let x: number = 3;
// let y: any = x;

// let z: any = 3;
// let k: number = z;

// function go(value:number,readRecordCount:number=1){

// }
// go(1);


//console.log(getMessage(6).sendmessage);
getMessage("image", 2).forEach((msg) => {
  console.log(msg);
})

export { }