ts 函数声明或者约束的方式

代码

• interface 方式

interface myFn7 {
  (a: string, b: string): string;
}


let myFn7Demo: myFn7 = function (a: string, b: string): string {
  return a + b;
}

console.log(myFn7Demo("a","b"), "myFn7Demo")

interface myFn8 {
  ['myfn1'](a: string, b: string): string;
}

let myObjxxx:myFn8={
  myfn1(a: string, b: string): string {
    return a + b;
  }
}

let result888=myObjxxx.myfn1("a","b")
console.log(result888,"result888")

• type 方式

type myfnType1=(a:string)=>string;

const myfn123:myfnType1=(a:string)=>{
  return a;
}

let resultyyy=myfn123("123")

console.log(resultyyy,"resultyyy")

函数args使用方式

type myfnType3=(a?:string,...args:string[])=>string;

const myfn333:myfnType3=(a:string,...args:string[])=>{
  console.log(args,"args") //其余参数形成一个数组
  return a+args.join("");
}

let resultyyy3=myfn333("123","sdlkjfsdf","sldfjsdfsj")

console.log(resultyyy3,"resultyyy3")

// type myfnType4=(...args:string[])=>string;

const myfn444=(...args:string[])=>{
  console.log(args,"args") //其余参数形成一个数组
  return args.join("");
}

let resultyyy4=myfn444("123","sdlkjfsdf","sldfjsdfsj")

console.log(resultyyy4,"resultyyy4")

...args 代表把所有的参数传递到args数组里面，用其他命名也可以