I spent two full days with microfilm this week in the NY public library reviewing the New York Daily News and The New York Herald from 1900 and 1902.
There were large clear pictures of the Giants in dark hats and dark socks in 1902. The NY public library did not have The News for 1900 and 1901 if you can believe it, so I was left with the small images of The Herald for 1900, but the dark hats were observable in 1900 as well. I did not review 1901. It appears a dark hat and socks was a road outfit or an alternate outfit uniform.
We need further research on uniform for the Giants 1900-1902, and to adjust our popular online references.