I wanted to use TypeScript in an existing SharePoint Add-In build with Visual Studio 2013.
So the first thing I did was add the TypeScript Add-In for Visual Studio.
Then I added a TypeScript file to my project.
I expected Visual Studio to generate my .js file, but it didn't.
This was because something was missing from the project file.
<Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\TypeScript\Microsoft.TypeScript.targets" />
After adding the piece of XML above to my project file my .js file was generated.