Better way to restrict object to certain attributes

Better way to restrict object to certain attributes

Suppose I have an object:
obj =
foo: 'foo'
bar: 'bar'
... and lots of other stuff ...
... these values vary, and are not actually hard coded ...
I'd like to create a copy of that object which contains only a subset of
its attributes.
obj2 =
foo: obj.foo
bar: obj.bar
// *doesn't* copy any other attributes from `obj`
Is there a more idiomatic way of doing this? Something like
obj2 = copy_only obj, ['foo', 'bar']
I mean, sure, I could write copy_only myself, but I'm looking for the
idiomatic way to do this, not the home baked way. Is there such an idiom
that you can recommend for this scenario?