To avoid navigating manually to the correct directory use the “Open Command Line” extension from Mads Kristensen. It is available for free in the Marketplace. You find it here.
Once installed you can open a command prompt conviently directly from within Visual Studio.

Tipp: Use the Keyboard Shortcut ALT+Space instead of the context menu to open the command prompt.
You can then run your npm command:
npm install react-bootstrap-typeahead
As a side note: As of npm 5.0.0, installed modules are added as a dependency by default, so the –save option is no longer required.
Update 2019:
Developer Command Prompt and Developer Power Shell are now integrated into Visual Studio 2019 ( 16.2 Preview 2 ) – no need for an extension anymore.
You find them under Tools/Command Line
By default no shortcut is assigned – so you have to do this yourself.
