Simple code snippets I made while studying typescript.

You'll notice you can find most of them on the typescript website 😛 Then why'd I do this? Well just for fun 🤷‍♂️ 😁

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Prerequisites

1. JavaScript
2. NodeJS
3. npm

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Setup

src folder contains all the TS files and build folder contains the equivalent JS and declaration(*.d.ts) files.

Steps used to initialise a basic typescript node project :

1. npm init -y
2. npm install typescript nodemon @types/node --save-dev
3. npx tsc --init --rootDir src --outDir build --lib es6,dom --module commonjs --allowJs true --esModuleInterop --resolveJsonModule --noImplicitAny true

Step 3 is totally your choice which options you choose to enable and what values you prefer.

Option	Description
--rootDir	Folder where we put our Typescript code /src. Only use to control the output directory structure with --outDir.
--outDir	Typescript to JavaScript compiled code goes here.
--module	Specify module system for JavaScript files used in project.
--esModuleInterop	It instructs TypeScript to allow us to use an import like this import myModule from '../myModule' instead of import myModule = require('../myModule') even if your module system defines CommonJS. source ↗️
--lib	If your target is es5 but you will be using es6 or esnext features then you can specify it in this option. source ↗️
--allowJs	If you have JavaScript in your project, should it be compiled with Typescript.
--resolveJsonModule	Include modules imported with .json extension.
--noImplicitAny	Raise error on expressions and declarations with an implied any type.

Sources: Typescript Handbook | Understanding TypeScript Configuration Options

4. Create a nodemon.json file as following (So that you don't have to compile again and again after making changes, nodemon takes care of that.) :

  {
    "watch": ["src"],
    "ext": ".ts,.js",
    "ignore": [],
    "exec": "npx tsc"
  }

5. Change package.json as following :

  "scripts": {
    "start": "nodemon",
    "test": "echo \"Error: no test specified\" && exit 1"
  }

6. npm start. Your all the .ts files get compiled to .js in build folder and then you can run them using node ./build/<your_compiled_file.js>

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References:

1. https://www.typescriptlang.org/docs/handbook/intro.html
2. https://khalilstemmler.com/blogs/typescript/node-starter-project/
3. https://medium.com/javascript-in-plain-english/typescript-configuration-options-tsconfig-json-561d4a2ad4b