Member-only story

Why .ts Files Are Often Better Than .d.ts: A TypeScript Best Practice 🚀

Xiuer Old
2 min readJan 30, 2025

The Role of .d.ts Files 📜

.d.ts files serve a specific purpose in TypeScript:

  • They provide type descriptions for JavaScript code 📝
  • Act as blueprints for available types in your source code 🗺️
  • Can be seen as TypeScript’s version of header files 📄

For example:

// Declaration (.d.ts)
export function add(num1: number, num2: number): number;

// Implementation (.ts)
export function add(num1: number, num2: number): number {
return num1 + num2;
}

The Case for .ts Files 💪

While .d.ts files have their place, .ts files offer several advantages:

  1. Unified Development: Combine declarations and implementations in one file 🔗
  2. Improved Type Safety: TypeScript compiler checks .ts files more rigorously 🛡️
  3. Easier Maintenance: No need to keep separate declaration and implementation files in sync 🔄
  4. Automatic Generation: You can generate .d.ts files from .ts files when needed 🔧

Configuring Your Project ⚙️

--

--

Xiuer Old
Xiuer Old

Written by Xiuer Old

🔥Little brother teaches front-end and AI online🌈

Responses (1)