Dev Mode in Visual Studio

Dev Mode is a new feature for TypeScript 1.4 and higher that allows you to

1. Use a custom language service file of your choosing.
2. Debug the script side of the language service Visual Studio is using during a session.

Enabling Dev Mode

In Visual Studio 2013

1. Open up the Registry Editor (regedit.exe from the Run prompt).
2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\12.0\TypeScriptLanguageService (or create the key if it does not exist).
3. Create a new DWORD (32-bit) Value with the name EnableDevMode.
4. Right click the EnableDevMode value and Modify it.
5. Change the Value data to 1.

In Visual Studio 2015

1. Open up the Registry Editor (regedit.exe from the Run prompt).
2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\14.0\TypeScriptLanguageService (or create the key if it does not exist).
3. Create a new DWORD (32-bit) Value with the name EnableDevMode.
4. Right click the EnableDevMode value and Modify it.
5. Change the Value data to 1.

Using a custom language service file

1. [Enable dev mode](#Enabling Dev Mode)

Debugging the language service