Generate TypeScript Declaration Files for JavaScript Files
Here’s the way you can generate TypeScript declaration files for your JavaScript project
Originally published on my website
I’ve been moving a few utilities that I use in multiple projects to npm libraries. But I needed an easy, reliable way to generate TypeScript declarations, since I primarily use TypeScript.
1. Open your project and ensure you have a package.json
2. Install the typescript
library as a development dependency
- With
pnpm
:pnpm i -D typescript
- With
npm
:npm i -D typescript
- With
yarn
:yarn add typescript -D
3. Add the prepare
script to the scripts
object in package.json
For example, mine looks like this:
"scripts": {
"prepare": "tsc --declaration --emitDeclarationOnly --allowJs index.js"
},
This command runs tsc
, the TypeScript compiler, and tells it to only generate .d.ts
files (declaration files). Be sure to replace index.js
with your JavaScript files.
- With
pnpm
:pnpm prepare
orpnpm run prepare
- With
npm
:npm run prepare
- With
yarn
:yarn run prepare
If you have any questions, send a tweet my way. I hope that this guide comes in handy for you, thanks for reading!