Creating TypeScript declaration file for exporting JavaScript function

Question

Creating TypeScript declaration file for exporting JavaScript function

I'm a beginner with TypeScript and I want to learn how to create a declaration file for a custom JavaScript function. I attempted to do this, however, I encountered an error stating "Could not find a declaration file for module './main'." Additionally, IntelliSense is not working in the index.ts file.

main.js

var maths={ sum:function (a,b){ console.log(a+b)}}

module.exports=maths;

index.ts

import * as mt from "./main"
mt.sum(2,5);

type.d.ts

 declare module 'main' {
export function sum(a:number,b:number):void }

`

javascript typescript

Answer 1

Answer №1

When you use this import statement:

import * as mt from "./main"

It is searching for either main.ts or main.d.ts in the same folder as index.ts.

To resolve this, you can try renaming type.d.ts to main.d.ts, and removing declare module 'main' from it. Keep only export function sum at the top level. By importing it this way, the module name will be derived from the file name. You may need to also remove the reference to type.d.ts from your project (or tsconfig.json) if applicable.

Alternatively, you could modify the import statement to:

import * as mt from "main"

This ensures that the module name matches exactly the one specified in declare module.

Answer 2

When you use this import statement:

import * as mt from "./main"

It is searching for either main.ts or main.d.ts in the same folder as index.ts.

To resolve this, you can try renaming type.d.ts to main.d.ts, and removing declare module 'main' from it. Keep only export function sum at the top level. By importing it this way, the module name will be derived from the file name. You may need to also remove the reference to type.d.ts from your project (or tsconfig.json) if applicable.

Alternatively, you could modify the import statement to:

import * as mt from "main"

This ensures that the module name matches exactly the one specified in declare module.

Creating TypeScript declaration file for exporting JavaScript function

Answer №1

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