typeScript--[interface接口实现类的定义，函数定义，可索引定义]

一.定义函数接口

interface Fn {
  (name: string): void;
}
var fn: Fn = function (name): void {
  console.log(name);
};
fn("逍遥的码农");

 二.定义类的接口

定义类需要用到关键字implements跟上定义的接口

interface Me {
  name: string;
  age: number;
  say(): void;
}
class My implements Me { //定义类需要用到关键字implements
  name: string;
  age: number;
  constructor(name: string, age: number) {
    this.name = name;
    this.age = age;
  }
  say(): void {
    console.log(this.name + this.age);
  }
}

三.可索引接口

1.数组（数组下标为number类型 index可以自定义）

interface Indexable {
  [index: number]: string;
}
var arr: Indexable = ["a", "b", "c"];
console.log(arr[0]);

2.对象（对象的key为string类型 key可以自定义）

interface Obj {
  [key: string]: string;
}
var obj: Obj = {
  name: "逍遥的码农",
};
console.log(obj.name);