Yep. JS doesn't have a standard library so npm is the best we've got. And speaking of the best we've got, the XSD validator above is the only one I'm aware of

Yep. JS doesn't have a standard library so npm is the best we've got. And speaking of the best we've got, the XSD validator above is the only one I'm aware of on npm—kind of shocking given how many overall libraries there are. It speaks to the unpopularity of XSDs among web devs, which is ironic since HTML is XML.