nodejs在typescript專案中申明全域性變數

這樣做的目的是避免迴圈引用，編寫多餘的型別檔案

//global.d.ts

import type { A } from "./a";
import type { B } from "./b";

declare global {
  var a: A;
  var b: B;
}

//index.ts

import { A } from "./a";
import { B } from "./b";

global.a = new A();
global.b = new B();

a.a();
b.b();

//a.ts

export class A {
  a() {
    console.log('a');
    b.b();
  }
  a2() {
    console.log('a2');
  }
}

//b.ts

export class B {
  b() {
    console.log('b');
    a.a2();
  }
}