this a proposal for a non zero exit value for npm outdated.

if dependencies are found that don't match the specification from the package.json, either if they are wrong (red) or outdated (yellow) the command should return a value that is not zero.

this feature could be utilized to invalidate a build if dependencies are not up to date any more.

by default the return value should be zero, via a cli parameter the level should be configurable. e.g. return non zero if there are errors (red) or non zero if there are warnings.

if this proposal finds acceptance i'll be happy to devise a pull request.