Setting up Express Server 📡 with TypeScript

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Express.js is a web application framework that is built on top of Node.js. It provides a minimal interface with all the tools required to build a web application. Express.js adds flexibility to an application with a huge range of modules available on npm that you can directly plug into Express as per requirement.

Step 1: Create a .gitignore file

node_modules/
.env

Step 2: Add dependencies

You may use yarn or npm (I am using yarn here).

yarn add for dependencies
yarn add -D for dev dependencies

NOTE: We might add more later on… and discuss them as we move along. Also, the version may be newer for you or some of the packages may be deprecated in the future. Also as we are using typescript we require type-definitions (@types) of all dependencies we have added

The dependencies shown below are the basic ones I think are required for the server to be up and running.

"dependencies": {
    "colors": "^1.4.0",
    "cors": "^2.8.5",
    "dotenv": "^8.2.0",
    "express": "^4.17.1",
  },
  "devDependencies": {
    "@types/cors": "^2.8.9",
    "@types/express": "^4.17.9",
    "concurrently": "^5.3.0",
    "nodemon": "^2.0.6"
  }

Step 3: Create tsconfig.json file and add the following

Configuring TypeScript

You might want to look at the official documentation providing more insights for configuring TypeScript and study more parameters available and use according to your needs.

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es6" /* Specify ECMAScript target version. */,
    "module": "commonjs" /* Specify module code generation. */,
    "sourceMap": false /* Generates corresponding '.map' file. */,
    "outDir": "./dist" /* Redirect output structure to the directory. */,
    "rootDir": "./src" /* Specify the root directory of input files. */,

    /* Strict Type-Checking Options */
    "strict": true /* Enable all strict type-checking options. */,

    /* Module Resolution Options */
    "moduleResolution": "node" /* Specify module resolution strategy. */,
    "baseUrl": "./" /* Base directory to resolve non-absolute module names. */,
    "paths": {
      "*": ["node_modules/", "src/types/*"]
    } ,
    "esModuleInterop": true ,

    /* Advanced Options */
    "skipLibCheck": true /* Skip type checking of declaration files. */,
    "forceConsistentCasingInFileNames": true 
  },
  "include": ["src/**/*"],
"exclude": ["src/types/*.ts", "node_modules", ".vscode"]
}

Step 4: Create the main file

Create an src folder in your directory and add an app.ts file with the following contents to get your express server up and running.

Relative Path: src/app.ts

import express, { Application, json, Request, Response } from "express";
import "colors";
import cors from "cors";
import { config } from "dotenv";

config();

const app: Application = express();

app.use(cors());
app.use(json());

const PORT: string | number = process.env.PORT || 5000;
const ENV: string = process.env.NODE_ENV || "development";

app.get("/", (_req: Request, res: Response) => {
  return res.send("API Running...");
});

app.listen(PORT, () =>
  console.log(
    ` 📡 Backend server: `.inverse.yellow.bold +
      ` Running in ${ENV} mode on port ${PORT}`
  )
);

Step 5: Setting up running scripts

Add the following to the package.json file

"scripts": {
    "watch-ts": "tsc -w",
    "server": "nodemon dist/app.js",
    "dev": "concurrently -k -p \"[{name}]\" -n \"Typescript,Node\" -c \"blue.bold,yellow.bold\" \"yarn run watch-ts\" \"yarn run server\" "
  }

Now run “ yarn run dev “ to start our server and voila we have our server up and running.

Output

You should see this as your output in the terminal and dist/ directory should appear in your project containing all the JavaScript code with ES6 syntax.

Also, there’s a ts-node package that runs node server using TypeScript files without any need to generate any JavaScript files.

Originally published at https://dev.to on January 30, 2021.