46. ​​Using TypeScript in NodeJS projects

Chapter 46: Using TypeScript in NodeJS Projects

On the journey of learning NodeJS, using TypeScript is an essential step to improve the quality of your code and make development more efficient. TypeScript is a superset of JavaScript that adds static typing and a few other features to the language. This means that all valid JavaScript code is also valid TypeScript code. The advantage of TypeScript is that it allows you to write code that is easier to understand and less error-prone.

To start using TypeScript in your NodeJS project, the first step is to install TypeScript as a development dependency. This can be done with the following command:

npm install --save-dev typescript

After installation, you need to create a TypeScript configuration file (tsconfig.json) in the root of your project. This file contains several options that control the behavior of the TypeScript compiler. Here is an example of a basic tsconfig.json file:

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "outDir": "./dist",
    "strict": true,
    "esModuleInterop": true
  }
}

In this file, we are defining that TypeScript should compile our code to ES6, use the CommonJS module system, place the compiled code in the dist folder, and enable strict checks.

Once TypeScript is set up, you can start writing your code in TypeScript. Let's start by creating an index.ts file in the root of your project with the following content:

import express from 'express';
const app = express();
app.get('/', (req, res) => {
  res.send('Hello World!');
});
app.listen(3000, () => {
  console.log('App is listening on port 3000');
});

This is a simple express server written in TypeScript. Note that we are using the ES6 import syntax, which is supported by TypeScript but not by NodeJS. TypeScript will compile this to the require() syntax that NodeJS understands.

To compile your TypeScript code to JavaScript, you can use the following command:

npx tsc

This will compile all TypeScript files in your project and place the resulting JavaScript code in the dist folder as specified in your tsconfig.json file.

To run your compiled JavaScript code, you can use the following command:

node dist/index.js

This should start your express server and display "App is listening on port 3000" in the console.

To make the development process more efficient, you can automate the compilation and execution of your code using a module like nodemon or ts-node. Nodemon will watch your TypeScript files and recompile them and restart your server whenever they change. Ts-node allows you to run your TypeScript code directly without having to compile it first.

In summary, TypeScript is a powerful tool that can help improve the quality of your code and make development more efficient. If you're developing APIs in NodeJS, it's definitely worth investing some time to learn TypeScript.

Next page of the Free Ebook:

148Refactoring a NodeJS API to TypeScript

3 minutes