ts namespace namespace, triple slash instruction, declaration file (declare declares ts variable function third-party module, etc.)

ts namespace namespace

ts namespace namespace

// namespace 命名空间
namespace A {
    
    
  export interface AAA {
    
    
    name: string;
  }
  export const arr: AAA[] = [{
    
     name: "ppp" }];
  export namespace B {
    
    
    export const bbb = "bbb";
  }
}
console.log("arr", A.arr);
// 简化命名空间
import BBB = A.B;

ts three slash instructions (introduce other .ts files)

• Or install the declaration file npm i @types/node -D

app.ts

namespace AAA {
    
    
  export const bbb = "bb";
}

index.ts

// index.ts入口文件 引入 app.ts文件
// ///<reference path="app.ts" />
// namespace AAA {
    
    
//   export const aaa = "aa";
// }
// 都可以使用 AAA.aaa AAA.bbb
// AAA.aaa
// AAA.bbb

// 使用声明文件
///<reference types="node" />
// AAA.bbb

ts declaration file d.ts - declare

• Install

  •   npm i 
      tsc --init
      npm i express
      npm i axios
    

01: declare declare express third-party module

typings Write declaration files for code or third-party modules

declare module "express" {
    
    
  interface Router {
    
    
    get(path: string, cb?: (req: any, res: any) => void): void;
  }
  // app.use("./api", router); 定义app.use的声明文件
  interface App {
    
    
    use(path: string, router: any): void;
    listen(port: number, cb?: () => void);
  }
  interface Express {
    
    
    (): App;
    Router(): Router;
  }
  const express: Express;
  export default express;
}

declare var a: boolean;
declare var add = (a: number, b: number) => number;

index.ts

import express from "express";

const app = express();
const router = express.Router();
app.use("./api", router);
router.get("/api", (req, res) => {
    
    
  res.json({
    
    
    code: 200,
  });
});

app.listen(9001, () => {
    
    
  console.log("服务器已起 端口为9001");
});

// a = true; => 找不到名称“a” 在typings下的 express下声明文件了a 则不会报错了 => declare var a: boolean;
a = true;
// 在typings下的 express下声明文件了a 则不会报错了 => declare var add = (a: number, b: number) => number;
add = (a: number, b: number) => {
    
    
  return a + b;
};
add(1, 2);

02: declare declares variables and functions

typings / app.d.ts

declare var b: boolean;
declare var add = (a: number, b: number) => number;
declare var sub = (a: number, b: number) => number;

app.ts

b = true;
add = (a: number, b: number) => {
    
    
  return a + b;
};
add(1, 2);
sub = (a: number, b: number) => {
    
    
  return a - b;
};
sub(1, 2);

index.ts

///<reference path="app.ts" />