[Feature Request] Add --bundle-relative flag

[loynoir]

Feature Request

Add --bundle-relative flag, only bundle all relative-alike files.

Scenario

Relative import may conflict, when using output extension .mjs.

#1563

Maybe

• add extension name to relative importId,
• or eliminate relative import doing a minimal bundling.

Description

import foo from '{{importId}}'

importId	bundle	Description
./foo	true	relative import
/{{packageRoot}}/foo	true	absolute import
/{{outside}}/foo	false	absolute import
#foo	true	subpath import
foo	false	namespace import and all else

#foo

https://nodejs.org/api/packages.html#packages_subpath_patterns

[hyrious]

You can write a plugin using onResolve to externalize paths outside of cwd.

[loynoir]

@hyrious
It can.

But esbuild is awesome for out-of-box experience for typescript. Maybe add an external preset or something?

Or any plan for issue #1563?

[evanw]

TypeScript's upcoming version 4.5 now has a way to do this. If you have a TypeScript file that needs to import another TypeScript file that will have a .mjs extension when compiled, you should use the .mts file extension for the TypeScript file and you should use import "./deps.mjs" in your TypeScript code to import deps.mts. This will be the official way to do it going forward and doesn't need any special support from esbuild. You can read the announcement here: https://devblogs.microsoft.com/typescript/announcing-typescript-4-5-beta/#new-file-extensions.

Closing this issue since this is being addressed outside of esbuild by the TypeScript team, and is possible to implement within esbuild via a plugin without needing to modify esbuild itself.