feat(ts): ban cjs exports in ts file (#167)

packages/eslint-plugin-antfu/src/rules/no-ts-export-equal.ts

@@ -0,0 +1,35 @@
+import { createEslintRule } from '../utils'
+
+export const RULE_NAME = 'no-ts-export-equal'
+export type MessageIds = 'noTsExportEqual'
+export type Options = []
+
+export default createEslintRule<Options, MessageIds>({
+  name: RULE_NAME,
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'Do not use `exports =`',
+      recommended: false,
+    },
+    schema: [],
+    messages: {
+      noTsExportEqual: 'Use ESM `export default` instead',
+    },
+  },
+  defaultOptions: [],
+  create: (context) => {
+    const extension = context.getFilename().split('.').pop()
+    if (!['ts', 'tsx', 'mts', 'cts'].includes(extension))
+      return {}
+
+    return {
+      TSExportAssignment(node) {
+        context.report({
+          node,
+          messageId: 'noTsExportEqual',
+        })
+      },
+    }
+  },
+})