interface Animal{ name:string; wan: ()=>string; } let Dog:Animal = { name:"lala", wan: ():string=>{return "wangwang"} } console.log( Dog.wan() ) class Cat implements Animal{ name:string wan():string{ return this.name + "miaomiao" } constructor(giveName:string) { this.name = giveName } } let cat = new Cat("huahua") console.log( cat.wan() )