`libReplacement: true` lookup folder should be configurable (via `typeRoots` ?)

[freshp86]

🔎 Search Terms

When libReplacement: true is used, for example

  "libReplacement": true,
  "lib": ["dom", "esnext"],

It is currently not possible to instruct the TS compiler to look for @typescript/lib-dom/ in a custom folder, which makes it impossible to leverage libReplacement: true in setups where the folder does not reside in the parent chain (real-world scenario in the Chromium repository). For example adding something as follows has no effect.

   "typeRoots": [
      "./some/sibling/folder/node_modules/@typescript",         <-- Does not work
      "./some/sibling/folder/node_modules/@typescript/lib-dom"  <-- Does not work either
   ],

Pasting --traceResolution output for reference.

======== Resolving module '@typescript/lib-dom' from '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/resources/tools/eslint/__lib_node_modules_lookup_lib.dom.d.ts__.ts'. ========
Explicitly specified module resolution kind: 'Node10'.
Loading module '@typescript/lib-dom' from 'node_modules' folder, target file types: TypeScript, Declaration.
Searching all ancestor node_modules directories for preferred extensions: TypeScript, Declaration.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/resources/tools/eslint/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/resources/tools/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/resources/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/out/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/src/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/chromium/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/workspace/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/home/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/local/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/usr/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Directory '/node_modules' does not exist, skipping all lookups in it.
Scoped package detected, looking in 'typescript__lib-dom'
Loading module '@typescript/lib-dom' from 'node_modules' folder, target file types: JavaScript.
Searching all ancestor node_modules directories for fallback extensions: JavaScript.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/resources/tools/eslint/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/resources/tools/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/resources/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/webui/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/ui/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/gen/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/out/gchrome/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/out/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/src/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/chromium/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/workspace/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/home/node_modules' does not exist, skipping all lookups in it.                                                                                                                                                            
Directory '/usr/local/home/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/local/node_modules' does not exist, skipping all lookups in it.
Directory '/usr/node_modules' does not exist, skipping all lookups in it.
Directory '/node_modules' does not exist, skipping all lookups in it.
======== Module name '@typescript/lib-dom' was not resolved. ========

Or if typeRoots is not the right way, there should be some way to customize where to look.

Let me know if you think a minimal repro is needed. Skipping for now as the above setup seems easy to reproduce.

🕗 Version & Regression Information

Reproducing on v 6.0.2. Did not try previous versions.

🙁 Actual behavior

No way exists to tell tsc where to locate the @typescript/lib-dom/ folder.

🙂 Expected behavior

There should be a way tell tsc where to locate the @typescript/lib-dom/ folder, similar to how this is done with typeRoots for types listed in types.

[MartinJohns]

Shouldn't it work if you point to your local package via devDependencies in your packages.json file?

[MARIUAM]

This looks like a valid concern, especially for monorepos or complex builds like Chromium where node_modules aren't always in the parent chain. Is there any workaround currently available, or does the compiler logic specifically restrict @typescript/lib- lookups to standard node resolution?

[RyanCavanaugh]

🤖 Thank you for your issue! I've done some analysis to help get you started. This response is automatically generated; feel free to 👍 or 👎 this comment according to its usefulness.

Similar Issues

Here are the most similar issues I found

• (71%) microsoft/typescript#37958: Folders from typesRoot should be used in looking up for types for imports as well as `@types` folder
• (69%) microsoft/typescript#34969: need "libRoots" in tsconfig.json for private node-runtime type definition
• (68%) microsoft/typescript#17284: Compile outputs js files correctly but shows error `TS2688 ` with `typeRoots` specified.
• (67%) microsoft/typescript#30855: Add option to include default typeRoots when overriding typeRoots
• (66%) microsoft/typescript#17511: Weird behavior of `typeRoots` option
• (65%) microsoft/typescript#44270: Compiler API: respect typeRoots in resolveModuleName
• (65%) microsoft/typescript#11383: Cannot use custom definitions in TS2
• (65%) microsoft/typescript#14979: TSConfig to support glob typeRoots
• (65%) microsoft/typescript#33183: Resolving hoisted `typeRoots` paths
• (65%) microsoft/typescript#13196: The typescript auto complete doesn't respond to typeRoots folders properly other than node_modules/@types

If your issue is a duplicate of one of these, feel free to close this issue. Otherwise, no action is needed.

Possibly Working as Intended

It looks like this behavior might be intentional. Here's what a computer had to say about it.

libReplacement turns the built-in libs into ordinary module imports like

import "@typescript/lib-dom";

Those imports are resolved with the same algorithm TypeScript uses for any
other bare module specifier: Node‐style directory walks that look for a
node_modules/@typescript/lib-dom directory in the current folder and every
ancestor. typeRoots is not part of module resolution; it only controls which
@types packages are automatically included once they are found. It therefore
has no effect on a bare import such as @typescript/lib-dom.

If the closest node_modules directory is not in the ancestor chain you have
three options that already exist today:

1. Physically place a node_modules/@typescript/lib-dom folder in an ancestor
   directory.

2. Use npm link, pnpm –shamefully-hoist, or any other package-manager
   mechanism that hoists the package into an ancestor node_modules.

3. Add an explicit path mapping in tsconfig.json:

   {
     "compilerOptions": {
       "baseUrl": ".",
       "paths": {
         "@typescript/lib-dom": [
           "./some/sibling/folder/node_modules/@typescript/lib-dom"
         ]
       }
     }
   }

Because a supported mechanism (paths/baseUrl, or the standard Node module
layout) already provides the needed configurability, the compiler’s current
behavior is correct and no new option is required.

[RyanCavanaugh]

typeRoots changes how type directives are resolved, not modules, so isn't applicable here.

Or if typeRoots is not the right way, there should be some way to customize where to look.

Lib replacement is really just a convenience feature; if you have lib files in a different place that isn't resolvable through the normal means, you can always put them in files or include instead (plus set noLib).