Suggest enabling allowJs for an import from a .js(x) file

[JoshuaKGoldberg]

Suggestion

🔍 Search Terms

suggest allowJs js jsx extension import 7016

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

The error message for importing from a relative module that's not found is the same as a file that has a .js extension.

📃 Motivating Example

// index.ts
import { value } from "./values";
// By default: implicitly any
// With noImplicitAny: \
//   Could not find a declaration file for module './values'.
//   '/path/to/repo/values.js' implicitly has an 'any' type. ts(7016)

// values.js
export const value = "";

💻 Use Cases

Folks coming in fresh to TypeScript might not know allowJs is off by default.

Perhaps this suggestion text would be helpful?

A .js file exists at that location, but the 'allowJs' compiler option is not enabled.