🛠 Repo: Switch from CJS to ESM internally

[JoshuaKGoldberg]

Tooling Suggestion Checklist

• I have tried restarting my IDE and the issue persists.
• I have pulled the latest main branch of the repository.
• I have read and agree to Mocha's Code of Conduct and Contributing Guidelines
• I have searched for related issues and issues with the faq label, but none matched my issue.
• I want to provide a PR to resolve this

Overview

Mocha's source code is written in a legacy CommonJS (CJS) style right now. That means 'use strict' in source files, const ... = require(...), module.exports, etc.

Moving to ECMAScript Modules (ESM) would allow the code to integrate better with more modern dev tooling. Static analysis tools such as ESLint and TypeScript are better able to analyze ESM, for example: which will help with #4154 and #4228.

Also I find ESM to be a cleaner syntax. It's more semantically precise! 🙂

Suggestion: let's migrate internally from CJS to ESM?

Additional Info

This is blocked on #5358: bumping the minimum Node.js version to one that supports require(esm).

I suspect this should land as a part of Mocha 12 (#5357). Although it shouldn't be a breaking change on its own, it's very likely some users out there are depending on some internal structuring quirk. Having this be part of the 12 beta for a while will help test it out. And having it be part of a major will help shield us from protests of semver breakage.

[wnghdcjfe]

Hello.
I tried to solve this issue, so I did the following.
First, I touched only the reporter part.
1.Code converted CJS part to ESM.
2. Existing annotations have not been removed.
3. I left the variable or function name of the existing code.
4. If it is declared as a var in the code, it has been changed to const or let.

Is this the right way to do it?
...
After working on it, now I know it's in that state is not status: accepting prs haha.... Sorry..
I'll PR it more carefully next time

[mark-wiemer]

@wnghdcjfe draft PRs are always welcome, they can help us triage :)