jedwards1211 / node-export-map-bug

node-export-map-bug

This repo demonstrates inconsistent export map behavior in Node when a package is inside node_modules versus when it is not.

import "my-package" (the name of the root project) resolves to dist/esm/index.js which tries to import "my-package/foo.js". That should resolve to dist/esm/foo.js, but the presence of dist/esm/package.json with {"type": "module"} seems to break it.

However, with this exact same package structure in node_modules/my-package2, import "my-package2" doesn't have any errors - node_modules/my-package2/dist/esm/package.json doesn't seem to break the resolution in this case.

Running

Do not npm install! it would overwrite the node_modules directory I've set up to repro. Just run npm test:

> test
> ./test

+ echo package in local directory
package in local directory
+ node -e 'require("my-package")'
hello from /Users/andy/gh/node-export-map-bug/dist/cjs/index.js
hello from /Users/andy/gh/node-export-map-bug/dist/cjs/foo.js
+ node -e 'import("my-package")'
node:internal/errors:496
    ErrorCaptureStackTrace(err);
    ^

Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'my-package' imported from /Users/andy/gh/node-export-map-bug/dist/esm/index.js
    at new NodeError (node:internal/errors:405:5)
    at packageResolve (node:internal/modules/esm/resolve:781:9)
    at moduleResolve (node:internal/modules/esm/resolve:830:20)
    at defaultResolve (node:internal/modules/esm/resolve:1035:11)
    at DefaultModuleLoader.resolve (node:internal/modules/esm/loader:269:12)
    at DefaultModuleLoader.getModuleJob (node:internal/modules/esm/loader:153:32)
    at ModuleWrap.<anonymous> (node:internal/modules/esm/module_job:76:33)
    at link (node:internal/modules/esm/module_job:75:36) {
  code: 'ERR_MODULE_NOT_FOUND'
}

Node.js v20.3.0
+ echo equivalent package in node_modules
equivalent package in node_modules
+ node -e 'require("my-package2")'
hello from /Users/andy/gh/node-export-map-bug/node_modules/my-package2/dist/cjs/index.js
hello from /Users/andy/gh/node-export-map-bug/node_modules/my-package2/dist/cjs/foo.js
+ node -e 'import("my-package2")'
hello from file:///Users/andy/gh/node-export-map-bug/node_modules/my-package2/dist/esm/foo.js
hello from file:///Users/andy/gh/node-export-map-bug/node_modules/my-package2/dist/esm/index.js