Check that module preceeds import and require in exports definitions

pkg/index.d.ts

@@ -58,6 +58,8 @@ export type Message =
       }
     >
   | BaseMessage<'EXPORTS_TYPES_SHOULD_BE_FIRST'>
+  | BaseMessage<'EXPORTS_MODULE_SHOULD_PRECEED_IMPORT'>
+  | BaseMessage<'EXPORTS_MODULE_SHOULD_PRECEED_REQUIRE'>
   | BaseMessage<'EXPORTS_DEFAULT_SHOULD_BE_LAST'>
   | BaseMessage<'EXPORTS_MODULE_SHOULD_BE_ESM'>
   | BaseMessage<'EXPORTS_VALUE_INVALID', { suggestValue: string }>

pkg/src/index.js

@@ -493,6 +493,34 @@ export async function publint({ pkgDir, vfs, level, strict, _packedFiles }) {
         }
       }
 
+      // a 'module' export should always preceed 'require'
+      if (
+        'module' in exports &&
+        'require' in exports &&
+        exportsKeys.indexOf('module') > exportsKeys.indexOf('require')
+      ) {
+        messages.push({
+          code: 'EXPORTS_MODULE_SHOULD_PRECEED_REQUIRE',
+          args: {},
+          path: currentPath.concat('module'),
+          type: 'error'
+        })
+      }
+
+      // a 'module' export should always preceed 'import'
+      if (
+        'module' in exports &&
+        'import' in exports &&
+        exportsKeys.indexOf('module') > exportsKeys.indexOf('import')
+      ) {
+        messages.push({
+          code: 'EXPORTS_MODULE_SHOULD_PRECEED_IMPORT',
+          args: {},
+          path: currentPath.concat('module'),
+          type: 'error'
+        })
+      }
+
       // the default export should be the last condition
       if (
         'default' in exports &&

pkg/src/message.js

@@ -56,6 +56,12 @@ export function printMessage(m, pkg) {
     case 'EXPORTS_TYPES_SHOULD_BE_FIRST':
       // prettier-ignore
       return `${c.bold(fp(m.path))} should be the first in the object as required by TypeScript.`
+    case 'EXPORTS_MODULE_SHOULD_PRECEED_REQUIRE':
+      // prettier-ignore
+      return `${c.bold(fp(m.path))} should come before 'require' so it can take precedence when used by a bundler.`
+    case 'EXPORTS_MODULE_SHOULD_PRECEED_IMPORT':
+      // prettier-ignore
+      return `${c.bold(fp(m.path))} should come before 'import' so it can take precedence when used by a bundler.`
     case 'EXPORTS_DEFAULT_SHOULD_BE_LAST':
       // prettier-ignore
       return `${c.bold(fp(m.path))} should be the last in the object so it doesn't take precedence over the keys following it.`

pkg/tests/fixtures/exports-module/main.js

@@ -0,0 +1 @@
+module.exports = 'foo'

pkg/tests/fixtures/exports-module/main.mjs

@@ -0,0 +1 @@
+export const foo = 'bar'

pkg/tests/fixtures/exports-module/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "publint-test-exports-module",
+  "version": "0.0.1",
+  "private": true,
+  "exports": {
+    ".": {
+      "import": "./main.mjs",
+      "require": "./main.js",
+      "module": "./main.mjs"
+    }
+  }
+}

pkg/tests/playground.js

@@ -28,6 +28,11 @@ testFixture('missing-files', [
 
 testFixture('no-exports-module', [])
 
+testFixture('exports-module', [
+  'EXPORTS_MODULE_SHOULD_PRECEED_REQUIRE',
+  'EXPORTS_MODULE_SHOULD_PRECEED_IMPORT'
+])
+
 testFixture('publish-config', ['USE_EXPORTS_BROWSER', 'FILE_DOES_NOT_EXIST'])
 
 testFixture('test-1', ['TYPES_NOT_EXPORTED', 'FILE_INVALID_FORMAT'])

site/rules.md

@@ -57,6 +57,14 @@ If the `exports` field contains glob paths, but it doesn't match any files, repo
 
 The `exports` field should not have globs defined with trailing slashes. It is [deprecated](https://nodejs.org/docs/latest-v16.x/api/packages.html#subpath-folder-mappings) and should use [subpath patterns](https://nodejs.org/api/packages.html#subpath-patterns), e.g. a trailing `/*` instead.
 
+## `EXPORTS_MODULE_SHOULD_PRECEED_IMPORT`
+
+Ensure `module` condition to come before `import` condition. Due to the way conditions are matched top-to-bottom, the `module` condition (used in bundler contexts only) must come before an `import` definition, so it has the opportunity to take precedence.
+
+## `EXPORTS_MODULE_SHOULD_PRECEED_REQUIRE`
+
+Ensure `module` condition to come before `require` condition. Due to the way conditions are matched top-to-bottom, the `module` condition (used in bundler contexts only) must come before a `require` definition, so it has the opportunity to take precedence.
+
 ## `EXPORTS_TYPES_SHOULD_BE_FIRST`
 
 Ensure `types` condition to be the first. The [TypeScript docs](https://www.typescriptlang.org/docs/handbook/esm-node.html#packagejson-exports-imports-and-self-referencing) recommends so, but it's also because the `exports` field is order-based.