TypeScript-函数

1、函数类型表达式

// 使用类型别名
type GreetFunction = (a:string)=>void
function greeter(fn:GreetFunction){
  fn('hello world')
}

function printToConsole(s:string){
  console.log(s);
  
}
greeter(printToConsole)

2、调用签名

type DescribableFunction = {
  description:string,
  (someAag:number):boolean
}
function doSomething(fn:DescribableFunction){
  console.log(fn.description+' returned '+fn(6));
  
}
function fn1(n:number){
  console.log(n);
  return true
}
fn1.description = 'hello'
doSomething(fn1)

3、构造签名

class Ctor{
  s:string
  constructor(s:string){
    this.s = s
  }
}

type SomeConstructor = {
  new (s:string):Ctor
}

function fn(ctor:SomeConstructor){
  return new ctor('hello')
}

const f = fn(Ctor)
console.log(f.s);