Provide a reliable way to find the entrypoint path or URL

What is the problem this feature will solve?

This solves the same problem as require.main.filename did in a CommonJS-only world: finding the entrypoint script for the Node.js process. This is most commonly used to determine the whether the current file is the entrypoint, but is also useful for various other sorts of introspection about the running Node.js environment. My specific use-case is finding a sensible default base URL to use to replicate Node.js's package resolution algorithm.

What is the feature you are proposing to solve the problem?

I suggest something like process.cliEntrypoint or process.cliMainUrl. I think it's important that any solution be usable regardless of whether the current module is CJS or ESM.

What alternatives have you considered?

require.main.filename provides this information but it doesn't work outside of CJS files, nor does it work if the entrypoint itself is ESM.

process.argv[1] sometimes provides this information, but it has a number of problems:

• If the Node.js CLI is run without a file extension, like node myapp instead of node myapp.js, process.argv[1] won't have an extension either.

• If the entrypoint is a symlink, process.argv[1] will point to the symlink instead of the physical JS file. This differs from __filename, which means it also differs from the logic used by require(). Note that npm exec always creates a symlink when running executables.

• process.argv is mutable, so it's possible for unrelated code to modify it in such a way that it's no longer usable to find the entrypoint.

Không có tệp triển khai hoặc bài kiểm thử nào được nêu. Hãy bắt đầu bằng việc xem xét cách Node.js hiện xác định entrypoint của CLI cho CommonJS và ESM, bao gồm các phương án thay thế require.main.filename và process.argv[1] được mô tả ở đây. Được xem là hoàn tất khi một API ổn định hoạt động với cả hai hệ thống module và xử lý các đường dẫn không có phần mở rộng, symlink và những thay đổi sau đó đối với process.argv.