"basic"/"relative" moduleResolution

まだ誰も着手していません。

### 🔍 Search Terms

module resolution, relative paths

### ✅ Viability Checklist

- [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code
- [x] This wouldn't change the runtime behavior of existing JavaScript code
- [x] This could be implemented without emitting different JS based on the types of the expressions
- [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
- [x] This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
- [x] This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

### ⭐ Suggestion

Hi all, I am writing a custom JavaScript runtime that only supports module imports using relative paths with file extensions present.

This is akin to browser-based module resolution (minus import maps).

At present, the `compilerOptions.moduleResolution` settings are:
- classic (deprecated)
- node/node10
- node16
- nodenext
- bundler

I think `classic` might work but am hesitant to use a deprecated feature.

Could we include a
```json
{
"compilerOptions": {
"moduleResolution": "relative"
}
}
```

That _only_ permits resolving module import paths that are relative to the current file and requires that import paths include file extensions?

```typescript
import * as foo from "./foo.js" // 👍
import * as foo from "./foo.ts" // 👍

import * as foo from "./foo" // 👎
import * as foo from "foo" // 👎
```

### 📃 Motivating Example

- Browsers using JavaScript modules without a bundler
- Custom JavaScript resolution algorithms
- (shameless plug) https://github.com/alshdavid/ion

### 💻 Use Cases

1. Accurate import semantics for consumers not using Node.js or contexts compatible with Node.js import resolution semantics

まず、コンパイラーが既存のモジュール解決オプション classic、node10、node16、nodenext、bundler をどのように処理しているかを読みます。compilerOptions.moduleResolution のエントリーポイントを追跡し、相対インポートとパッケージインポートに関する現在のテストを比較します。新しい相対モードが拡張子付きの相対インポートを受け入れ、拡張子のないインポートと相対でないインポートを拒否し、要求された例をカバーできれば完了です。

索引モデルが issue の本文から書いたものです。