Add a warning for jsnext field

pkg/index.d.ts

@@ -106,6 +106,7 @@ export type Message =
         browserishCondition: string
       }
     >
+  | BaseMessage<'DEPRECATED_FIELD_JSNEXT'>
 
 export interface Options {
   /**

pkg/src/index.js

@@ -196,28 +196,44 @@ export async function publint({ pkgDir, vfs, level, strict, _packedFiles }) {
 
   // check file existence for other known package fields
   const knownFields = [
-    'types',
-    'typings',
-    'jsnext:main',
-    'jsnext',
-    'unpkg',
-    'jsdelivr'
+    { name: 'types' },
+    { name: 'typings' },
+    {
+      name: 'jsnext:main',
+      deprecatedCode: /** @type {const} */ ('DEPRECATED_FIELD_JSNEXT')
+    },
+    {
+      name: 'jsnext',
+      deprecatedCode: /** @type {const} */ ('DEPRECATED_FIELD_JSNEXT')
+    },
+    { name: 'unpkg' },
+    { name: 'jsdelivr' }
   ]
   // if has typesVersions field, it complicates `types`/`typings` field resolution a lot.
   // for now skip it, but further improvements are tracked at
   // https://github.com/bluwy/publint/issues/42
   if (getPublishedField(rootPkg, 'typesVersions')[0]) {
     knownFields.splice(0, 2)
   }
-  for (const field of knownFields) {
-    const [fieldValue, fieldPkgPath] = getPublishedField(rootPkg, field)
+  for (const { name: fieldName, deprecatedCode } of knownFields) {
+    const [fieldValue, fieldPkgPath] = getPublishedField(rootPkg, fieldName)
     if (
       fieldValue != null &&
       ensureTypeOfField(fieldValue, ['string'], fieldPkgPath)
     ) {
       promiseQueue.push(async () => {
         const fieldPath = vfs.pathJoin(pkgDir, fieldValue)
-        await readFile(fieldPath, fieldPkgPath, ['.js', '/index.js'])
+        const hasContent =
+          (await readFile(fieldPath, fieldPkgPath, ['.js', '/index.js'])) !==
+          false
+        if (hasContent && deprecatedCode) {
+          messages.push({
+            code: deprecatedCode,
+            args: {},
+            path: fieldPkgPath,
+            type: 'warning'
+          })
+        }
       })
     }
   }

pkg/src/message.js

@@ -147,6 +147,9 @@ export function formatMessage(m, pkg) {
     case 'EXPORTS_VALUE_CONFLICTS_WITH_BROWSER':
       // prettier-ignore
       return `${c.bold(fp(m.path))} is ${c.bold(pv(m.path))} which also matches ${c.bold(fp(m.args.browserPath))}: "${c.bold(pv(m.args.browserPath))}", which overrides the path when building the library with the "${c.bold(m.args.browserishCondition)}" condition. This is usually unintentional and may cause build issues. Consider using a different file name for ${c.bold(pv(m.path))}.`
+    case 'DEPRECATED_FIELD_JSNEXT':
+      // prettier-ignore
+      return `${c.bold(fp(m.path))} is deprecated. ${c.bold('pkg.module')} should be used instead.`
     default:
       return
   }

pkg/tests/fixtures/deprecated-fields/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "publint-glob-deprecated",
+  "version": "0.0.1",
+  "private": true,
+  "main": "./index.js",
+  "jsnext": "./index.js",
+  "jsnext:main": "./index.js"
+}

pkg/tests/playground.js

@@ -134,6 +134,11 @@ testFixture('types-versions', [])
 
 testFixture('umd', ['FILE_INVALID_FORMAT', 'FILE_INVALID_FORMAT'])
 
+testFixture('deprecated-fields', [
+  'DEPRECATED_FIELD_JSNEXT',
+  'DEPRECATED_FIELD_JSNEXT'
+])
+
 /**
  * @typedef {{
  *  level?: import('../index.d.ts').Options['level']

site/rules.md

@@ -226,3 +226,7 @@ When matching the `"worker"` condition, it will resolve to `"./lib.server.js"` w
 This is usually not intended and causes the wrong file to be loaded. If it is intended, the `"worker"` condition should point to `"./lib.browser.js"` directly instead.
 
 To fix this, you can rename `"./lib.server.js"` to `"./lib.worker.js"` for example so it has its own specific file. Or check out the [USE_EXPORTS_OR_IMPORTS_BROWSER](#use_exports_or_imports_browser) rule to refactor away the `"browser"` field.
+
+## `DEPRECATED_FIELD_JSNEXT`
+
+The `"jsnext:main"` and `"jsnext"` fields are deprecated. The `"module"` field should be used instead. See [this issue](https://github.com/jsforum/jsforum/issues/5) for more information.

site/src/utils/message.js

@@ -141,6 +141,9 @@ function messageToString(m, pkg) {
     case 'EXPORTS_VALUE_CONFLICTS_WITH_BROWSER':
       // prettier-ignore
       return `${bold(pv(m.path))} matches ${bold(fp(m.args.browserPath))}: "${bold(pv(m.args.browserPath))}", which overrides the path when building the library with the "${bold(m.args.browserishCondition)}" condition. This is usually unintentional and may cause build issues. Consider using a different file name for ${bold(pv(m.path))}.`
+    case 'DEPRECATED_FIELD_JSNEXT':
+      // prettier-ignore
+      return `${bold(fp(m.path))} is deprecated. ${bold('pkg.module')} should be used instead.`
     default:
       return
   }