feat: 🎸 add .truncate() method

src/node-to-fsa/NodeFileSystemSyncAccessHandle.ts

@@ -55,6 +55,14 @@ export class NodeFileSystemSyncAccessHandle {
       throw error;
     }
   }
+
+  /**
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/FileSystemSyncAccessHandle/truncate
+   * @param newSize The number of bytes to resize the file to.
+   */
+  public async truncate(newSize: number): Promise<void> {
+    this.fs.truncateSync(this.fd, newSize);
+  }
 }
 
 export interface FileSystemReadWriteOptions {

src/node-to-fsa/__tests__/NodeFileSystemSyncAccessHandle.test.ts

@@ -112,4 +112,16 @@ maybe('NodeFileSystemSyncAccessHandle', () => {
       }
     });
   });
+
+  describe('.truncate()', () => {
+    test('can read from beginning', async () => {
+      const { dir } = setup({
+        'file.txt': '0123456789',
+      });
+      const entry = await dir.getFileHandle('file.txt');
+      const sync = await entry.createSyncAccessHandle!();
+      const res = await sync.truncate(5);
+      expect(res).toBe(undefined);
+    });
+  });
 });

src/node-to-fsa/types.ts

@@ -3,7 +3,7 @@ import type { IFs } from '..';
 /**
  * Required Node.js `fs` module functions for File System Access API.
  */
-export type NodeFsaFs = Pick<IFs, 'promises' | 'openSync' | 'fsyncSync' | 'statSync' | 'closeSync' | 'readSync'>;
+export type NodeFsaFs = Pick<IFs, 'promises' | 'openSync' | 'fsyncSync' | 'statSync' | 'closeSync' | 'readSync' | 'truncateSync'>;
 
 export interface NodeFsaContext {
   separator: '/' | '\\';