How can I trim trailing whitespace in Visual Studio 2012?

There are at least two extensions that can do this. One is CodeMaid which explicitly will trim trailing blanks on save, and the other is Productivity Power Tools which can run the Format Document automatically on save.

To add an extension from within Visual Studio 2012, select the Tools menu, then Extensions and Updates.., then in the window select Online on the left and enter your search string for CodeMaid or Productivity Power Tools in the box on the upper-right.

Ctrl + H
Find what:
[\u0020]+\r?\n
Replace with:
\r\n
\s instead of [\u0020] delete empty line feeds, probably because it matches line feeds...

You can use Mads Kristensen's Trailing Whitespace Visualizer. It has a keyboard shortcut to remove trailing whitespace from the current file. Ctrl+K, Ctrl+\

Note: this doesn't run on save, you have to explicitly run the command. On the bright side, it visually highlights the offending whitespace, so it's easier to identify cleanup opportunities even in code you haven't modified.