What are TypeScript declaration files

Short answer

Declaration files (.d.ts) describe the shape of JavaScript code to the TypeScript compiler. They enable type checking for libraries written in JavaScript. For reading and writing files in general, see python read write files. For module concepts, see python classes objects.

Steps

1. Create a .d.ts file alongside your JavaScript module
2. Declare exports: export function add(a: number, b: number): number;
3. For global libraries, use declare global or declare module
4. Reference types in tsconfig.json with "types" or "typeRoots"
5. Publish declarations by setting "declaration": true in tsconfig

Tips

• Install community types from @types/ packages when available
• Keep declarations in sync with the actual JavaScript implementation
• For error handling patterns, see python error handling try except