typescript-eslint · JoshuaKGoldberg · Jun 6, 2024 · Jun 3, 2024 · Jun 3, 2024 · Jun 3, 2024
diff --git a/docs/packages/Parser.mdx b/docs/packages/Parser.mdx
@@ -402,3 +402,31 @@ module.exports = {
 
 </TabItem>
 </Tabs>
+
+### `withoutProjectParserOptions(parserOptions)`
+
+Removes options that prompt the parser to parse the project with type information.
+In other words, you can use this if you are invoking the parser directly, to ensure that one file will be parsed in isolation, which is much faster.
+
+This is useful in cases where you invoke the parser directly, such as in an ESLint plugin context.
+
+```ts
+declare function withoutProjectParserOptions(
+  options: TSESTreeOptions,
+): TSESTreeOptions;
+```
+
+Example usage:
+
+```js title="somePlugin.js"
+const parser = require('@typescript-eslint/parser');
+
+function parse(path, content, context) {
+  const contextParserOptions = context.languageOptions?.parserOptions ?? {};
+  const parserOptions =
+    parser.withoutProjectParserOptions(contextParserOptions);
+
+  // Do something with the cleaned-up options eventually, such as invoking the parser
+  parser.parseForESLint(content, parserOptions);
+}
+```
diff --git a/packages/parser/src/index.ts b/packages/parser/src/index.ts
@@ -5,6 +5,7 @@ export {
   ParserServicesWithoutTypeInformation,
   clearCaches,
   createProgram,
+  withoutProjectParserOptions,
 } from '@typescript-eslint/typescript-estree';
 
 // note - cannot migrate this to an import statement because it will make TSC copy the package.json to the dist folder

diff --git a/packages/typescript-estree/src/index.ts b/packages/typescript-estree/src/index.ts
@@ -19,6 +19,7 @@ export { typescriptVersionIsAtLeast } from './version-check';
 export * from './getModifiers';
 export { TSError } from './node-utils';
 export * from './clear-caches';
+export { withoutProjectParserOptions } from './withoutProjectParserOptions';
 
 // note - cannot migrate this to an import statement because it will make TSC copy the package.json to the dist folder
 // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access

diff --git a/packages/typescript-estree/src/withoutProjectParserOptions.ts b/packages/typescript-estree/src/withoutProjectParserOptions.ts
@@ -0,0 +1,18 @@
+import type { TSESTreeOptions } from './parser-options';
+
+/**
+ * Removes options that prompt the parser to parse the project with type
+ * information. In other words, you can use this if you are invoking the parser
+ * directly, to ensure that one file will be parsed in isolation, which is much,
+ * much faster.
+ *
+ * @see https://github.com/typescript-eslint/typescript-eslint/issues/8428
+ */
+export function withoutProjectParserOptions(
+  opts: TSESTreeOptions,
+): TSESTreeOptions {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars -- The variables are meant to be omitted
+  const { EXPERIMENTAL_useProjectService, project, ...rest } = opts;
+
+  return rest;
+}
diff --git a/packages/typescript-estree/tests/lib/withoutProjectParserOptions.test.ts b/packages/typescript-estree/tests/lib/withoutProjectParserOptions.test.ts
@@ -0,0 +1,14 @@
+import { withoutProjectParserOptions } from '../../src';
+
+describe('withoutProjectParserOptions', () => {
+  it('removes only project parser options', () => {
+    const without = withoutProjectParserOptions({
+      comment: true,
+      EXPERIMENTAL_useProjectService: true,
+      project: true,
+    });
+    expect(without).toEqual({
+      comment: true,
+    });
+  });
+});