documentcloud/underscore — pull request #520 by moredip (2012-03-23 06:41:02+00:00)
Title: Add _.only(...), which pulls a subset of properties from an object

For example ```_.only( {one:1,two:2,three:3}, 'one', 'three' )``` yields ```{one:1, three:3}```

This is very useful for sanitizing/filtering input. This seems so useful that I suspect there might be a reason it isn't in underscore already...