Using `baseUrl` breaks package exports lookup

[mkubilayk]

Bug Report

A producer package exposes multiple entrypoints using Node's package exports. When this package is consumed using the following compiler options, TypeScript fails to resolve the entry points.

{
    "compilerOptions": {
        "module": "commonjs",
        "moduleResolution": "node16",
        "baseUrl": "/path/to/modules/store",
    }
}

This problem doesn't happen when baseUrl is absent -- relying on the default lookup behavior.

🔎 Search Terms

baseUrl, base url, package exports, module resolution

🕗 Version & Regression Information

This is the behavior in every version I tried: 4.7, 4.8 and 4.9.

I was unable to test this on prior versions because "node16" module resolution was first introduced in 4.7.

⏯ Playground Link

http://github.com/mkubilayk/typescript-package-exports-baseurl

💻 Code

Please see the full code and reproduction steps in the repo but the most relevant bits are as follows.

Producer:

{
    "name": "producer-with-package-exports",
    "version": "1.0.0",
    "main": "out/index.js",
    "types": "out/index.d.ts",
    "exports": {
        ".": {
            "types": "./out/index.d.ts",
            "require": "./out/index.js"
        },
        "./entrypoint-a": {
            "types": "./out/entrypoint-a.d.ts",
            "require": "./out/entrypoint-a.js"
        }
    }
}

Consumer (targetting "commonjs"):

import { something } from "producer-with-package-exports";
import { somethingElse } from "producer-with-package-exports/entrypoint-a";

🙁 Actual behavior

When using the baseUrl compiler option in the consumer "producer-with-package-exports/entrypoint-a" fails to resolve:

import { somethingElse } from "producer-with-package-exports/entrypoint-a";
//                            ^
// Cannot find module 'producer-with-package-exports/entrypoint-a' or its corresponding type declarations. ts(2307)

🙂 Expected behavior

Using baseUrl should not stop TypeScript from looking at package exports in the producer. So "producer-with-package-exports/entrypoint-a" should be resolved correctly -- matching the behaviour when baseUrl is not present.

---

I have also verified the producer package using @andrewbranch's https://arethetypeswrong.github.io (💙) and got the following report as expected:

Expand to see the full report

{
  "packageName": "producer-with-package-exports",
  "containsTypes": true,
  "entrypointResolutions": {
    ".": {
      "node10": {
        "name": ".",
        "resolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/index.d.ts",
          "isJson": false,
          "isTypeScript": true
        },
        "implementationResolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/index.js",
          "isJson": false,
          "isTypeScript": false
        },
        "trace": [
          "======== Resolving module 'producer-with-package-exports' from '/index.ts'. ========",
          "Explicitly specified module resolution kind: 'Node10'.",
          "Loading module 'producer-with-package-exports' from 'node_modules' folder, target file types: TypeScript, Declaration.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "File '/node_modules/producer-with-package-exports.ts' does not exist.",
          "File '/node_modules/producer-with-package-exports.tsx' does not exist.",
          "File '/node_modules/producer-with-package-exports.d.ts' does not exist.",
          "'package.json' does not have a 'typesVersions' field.",
          "'package.json' does not have a 'typings' field.",
          "'package.json' has 'types' field 'out/index.d.ts' that references '/node_modules/producer-with-package-exports/out/index.d.ts'.",
          "File '/node_modules/producer-with-package-exports/out/index.d.ts' exists - use it as a name resolution result.",
          "======== Module name 'producer-with-package-exports' was successfully resolved to '/node_modules/producer-with-package-exports/out/index.d.ts' with Package ID 'producer-with-package-exports/out/index.d.ts@1.0.0'. ========"
        ]
      },
      "node16-cjs": {
        "name": ".",
        "resolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/index.d.ts",
          "moduleKind": 1,
          "isJson": false,
          "isTypeScript": true
        },
        "implementationResolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/index.js",
          "moduleKind": 1,
          "isJson": false,
          "isTypeScript": false
        },
        "trace": [
          "======== Resolving module 'producer-with-package-exports' from '/index.ts'. ========",
          "Explicitly specified module resolution kind: 'Node16'.",
          "Resolving in CJS mode with conditions 'node', 'require', 'types'.",
          "File '/package.json' does not exist.",
          "Loading module 'producer-with-package-exports' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "Entering conditional exports.",
          "Matched 'exports' condition 'types'.",
          "Using 'exports' subpath '.' with target './out/index.d.ts'.",
          "File '/node_modules/producer-with-package-exports/out/index.d.ts' exists - use it as a name resolution result.",
          "Resolved under condition 'types'.",
          "Exiting conditional exports.",
          "======== Module name 'producer-with-package-exports' was successfully resolved to '/node_modules/producer-with-package-exports/out/index.d.ts' with Package ID 'producer-with-package-exports/out/index.d.ts@1.0.0'. ========"
        ]
      },
      "node16-esm": {
        "name": ".",
        "resolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/index.d.ts",
          "moduleKind": 1,
          "isJson": false,
          "isTypeScript": true
        },
        "trace": [
          "======== Resolving module 'producer-with-package-exports' from '/index.mts'. ========",
          "Explicitly specified module resolution kind: 'Node16'.",
          "Resolving in ESM mode with conditions 'node', 'import', 'types'.",
          "File '/package.json' does not exist.",
          "Loading module 'producer-with-package-exports' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "Entering conditional exports.",
          "Matched 'exports' condition 'types'.",
          "Using 'exports' subpath '.' with target './out/index.d.ts'.",
          "File '/node_modules/producer-with-package-exports/out/index.d.ts' exists - use it as a name resolution result.",
          "Resolved under condition 'types'.",
          "Exiting conditional exports.",
          "======== Module name 'producer-with-package-exports' was successfully resolved to '/node_modules/producer-with-package-exports/out/index.d.ts' with Package ID 'producer-with-package-exports/out/index.d.ts@1.0.0'. ========"
        ]
      },
      "bundler": {
        "name": ".",
        "resolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/index.d.ts",
          "isJson": false,
          "isTypeScript": true
        },
        "trace": [
          "======== Resolving module 'producer-with-package-exports' from '/index.ts'. ========",
          "Explicitly specified module resolution kind: 'Bundler'.",
          "File '/package.json' does not exist.",
          "Loading module 'producer-with-package-exports' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "Entering conditional exports.",
          "Matched 'exports' condition 'types'.",
          "Using 'exports' subpath '.' with target './out/index.d.ts'.",
          "File '/node_modules/producer-with-package-exports/out/index.d.ts' exists - use it as a name resolution result.",
          "Resolved under condition 'types'.",
          "Exiting conditional exports.",
          "======== Module name 'producer-with-package-exports' was successfully resolved to '/node_modules/producer-with-package-exports/out/index.d.ts' with Package ID 'producer-with-package-exports/out/index.d.ts@1.0.0'. ========"
        ]
      }
    },
    "./entrypoint-a": {
      "node10": {
        "name": "./entrypoint-a",
        "trace": [
          "======== Resolving module 'producer-with-package-exports/entrypoint-a' from '/index.ts'. ========",
          "Explicitly specified module resolution kind: 'Node10'.",
          "Loading module 'producer-with-package-exports/entrypoint-a' from 'node_modules' folder, target file types: TypeScript, Declaration.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "'package.json' does not have a 'typesVersions' field.",
          "File '/node_modules/producer-with-package-exports/entrypoint-a.ts' does not exist.",
          "File '/node_modules/producer-with-package-exports/entrypoint-a.tsx' does not exist.",
          "File '/node_modules/producer-with-package-exports/entrypoint-a.d.ts' does not exist.",
          "'package.json' does not have a 'typings' field.",
          "'package.json' has 'types' field 'out/index.d.ts' that references '/node_modules/producer-with-package-exports/entrypoint-a/out/index.d.ts'.",
          "Loading module as file / folder, candidate module location '/node_modules/producer-with-package-exports/entrypoint-a/out/index.d.ts', target file types: TypeScript, Declaration.",
          "File name '/node_modules/producer-with-package-exports/entrypoint-a/out/index.d.ts' has a '.d.ts' extension - stripping it.",
          "Directory '/node_modules/@types' does not exist, skipping all lookups in it.",
          "Loading module 'producer-with-package-exports/entrypoint-a' from 'node_modules' folder, target file types: JavaScript, JSON.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "'package.json' does not have a 'typesVersions' field.",
          "File '/node_modules/producer-with-package-exports/entrypoint-a.js' does not exist.",
          "File '/node_modules/producer-with-package-exports/entrypoint-a.jsx' does not exist.",
          "'package.json' has 'main' field 'out/index.js' that references '/node_modules/producer-with-package-exports/entrypoint-a/out/index.js'.",
          "Loading module as file / folder, candidate module location '/node_modules/producer-with-package-exports/entrypoint-a/out/index.js', target file types: JavaScript, JSON.",
          "File name '/node_modules/producer-with-package-exports/entrypoint-a/out/index.js' has a '.js' extension - stripping it.",
          "======== Module name 'producer-with-package-exports/entrypoint-a' was not resolved. ========"
        ]
      },
      "node16-cjs": {
        "name": "./entrypoint-a",
        "resolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts",
          "moduleKind": 1,
          "isJson": false,
          "isTypeScript": true
        },
        "implementationResolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/entrypoint-a.js",
          "moduleKind": 1,
          "isJson": false,
          "isTypeScript": false
        },
        "trace": [
          "======== Resolving module 'producer-with-package-exports/entrypoint-a' from '/index.ts'. ========",
          "Explicitly specified module resolution kind: 'Node16'.",
          "Resolving in CJS mode with conditions 'node', 'require', 'types'.",
          "File '/package.json' does not exist.",
          "Loading module 'producer-with-package-exports/entrypoint-a' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "Entering conditional exports.",
          "Matched 'exports' condition 'types'.",
          "Using 'exports' subpath './entrypoint-a' with target './out/entrypoint-a.d.ts'.",
          "File '/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts' exists - use it as a name resolution result.",
          "Resolved under condition 'types'.",
          "Exiting conditional exports.",
          "======== Module name 'producer-with-package-exports/entrypoint-a' was successfully resolved to '/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts' with Package ID 'producer-with-package-exports/out/entrypoint-a.d.ts@1.0.0'. ========"
        ]
      },
      "node16-esm": {
        "name": "./entrypoint-a",
        "resolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts",
          "moduleKind": 1,
          "isJson": false,
          "isTypeScript": true
        },
        "trace": [
          "======== Resolving module 'producer-with-package-exports/entrypoint-a' from '/index.mts'. ========",
          "Explicitly specified module resolution kind: 'Node16'.",
          "Resolving in ESM mode with conditions 'node', 'import', 'types'.",
          "File '/package.json' does not exist.",
          "Loading module 'producer-with-package-exports/entrypoint-a' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "Entering conditional exports.",
          "Matched 'exports' condition 'types'.",
          "Using 'exports' subpath './entrypoint-a' with target './out/entrypoint-a.d.ts'.",
          "File '/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts' exists - use it as a name resolution result.",
          "Resolved under condition 'types'.",
          "Exiting conditional exports.",
          "======== Module name 'producer-with-package-exports/entrypoint-a' was successfully resolved to '/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts' with Package ID 'producer-with-package-exports/out/entrypoint-a.d.ts@1.0.0'. ========"
        ]
      },
      "bundler": {
        "name": "./entrypoint-a",
        "resolution": {
          "fileName": "/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts",
          "isJson": false,
          "isTypeScript": true
        },
        "trace": [
          "======== Resolving module 'producer-with-package-exports/entrypoint-a' from '/index.ts'. ========",
          "Explicitly specified module resolution kind: 'Bundler'.",
          "File '/package.json' does not exist.",
          "Loading module 'producer-with-package-exports/entrypoint-a' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.",
          "Found 'package.json' at '/node_modules/producer-with-package-exports/package.json'.",
          "Entering conditional exports.",
          "Matched 'exports' condition 'types'.",
          "Using 'exports' subpath './entrypoint-a' with target './out/entrypoint-a.d.ts'.",
          "File '/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts' exists - use it as a name resolution result.",
          "Resolved under condition 'types'.",
          "Exiting conditional exports.",
          "======== Module name 'producer-with-package-exports/entrypoint-a' was successfully resolved to '/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts' with Package ID 'producer-with-package-exports/out/entrypoint-a.d.ts@1.0.0'. ========"
        ]
      }
    }
  },
  "fileExports": {
    "/node_modules/producer-with-package-exports/out/index.d.ts": {
      "something": {
        "name": "something",
        "flags": 2,
        "valueDeclarationRange": [
          21,
          35
        ]
      }
    },
    "/node_modules/producer-with-package-exports/out/index.js": {
      "__esModule": {
        "name": "__esModule",
        "flags": 1048580,
        "valueDeclarationRange": [
          14,
          75
        ]
      },
      "something": {
        "name": "something",
        "flags": 1048580,
        "valueDeclarationRange": [
          105,
          122
        ]
      }
    },
    "/node_modules/producer-with-package-exports/out/entrypoint-a.d.ts": {
      "somethingElse": {
        "name": "somethingElse",
        "flags": 2,
        "valueDeclarationRange": [
          21,
          39
        ]
      }
    },
    "/node_modules/producer-with-package-exports/out/entrypoint-a.js": {
      "__esModule": {
        "name": "__esModule",
        "flags": 1048580,
        "valueDeclarationRange": [
          14,
          75
        ]
      },
      "somethingElse": {
        "name": "somethingElse",
        "flags": 1048580,
        "valueDeclarationRange": [
          109,
          130
        ]
      }
    }
  }
}

[andrewbranch]

baseUrl is not a replacement for node_modules package lookups; it’s a replacement for relative paths. The implicit reasoning you have here is that when you have an import specifier like "package/subpath", we should always be looking for "/{some resolved prefix}/package/package.json" in order to figure out what to do with the /subpath portion of the path. But this logic is specific to node_modules lookups, and does not apply to baseUrl lookups (or paths, which are the other way you can resolve non-relative names). baseUrl is literally just a prefix to convert non-relative module specifiers to absolute ones, and was designed for use in AMD module loaders for browsers, like RequireJS. It shouldn’t be used for anything involving Node.

[typescript-bot]

This issue has been marked 'Working as Intended' and has seen no recent activity. It has been automatically closed for house-keeping purposes.