Auto Default File Extension

Automatically assigns a file extension when creating new files.

Decision order

1. autoDefaultFileExtension.enabled — default true.
   If false, the extension does nothing (workspace settings > user settings).

2. autoDefaultFileExtension.preferredExtension — if set, always use it
   (workspace settings > user settings).

3. autoDefaultFileExtension.autoSaveUntitled — default true.
   When you create an Untitled-X file, it will be saved as Untitled-X.[extension] at the workspace root (workspace settings > user settings).

4. Dominant extension in the workspace — if no preferred extension is set, the extension scans the workspace (respecting .gitignore) and uses the most frequent extension.

Note: Filenames that already contain a dot (including dotfiles like .gitignore) are not modified.

How to use

• Explorer → right-click a folder → “Create New File with Automatic Extension”.
• Or run the command via Ctrl+Alt+N (command: autoDefaultFileExtension.newFile).
• If you create a new file in the Explorer without an extension, the extension will rename it right after creation.
• If you create an Untitled file (e.g., via workbench.action.files.insertIntoNewFile or double-click in the tab bar):
  • With autoSaveUntitled: true, it’s saved as Untitled-X.[extension] in the workspace root.
  • With autoSaveUntitled: false, the editor’s language is set based on the preferred/dominant extension, but the file remains unsaved/untitled.

Settings

Example:

{
  "autoDefaultFileExtension.enabled": true,
  "autoDefaultFileExtension.preferredExtension": ".ts",
  "autoDefaultFileExtension.autoSaveUntitled": true
}