These are non-standard extensions to the Range interface introduced in 2006 and 2009 respectively: https://trac.webkit.org/changeset/48271 https://trac.webkit.org/changeset/16302
Docs: https://developer.mozilla.org/en-US/docs/Web/API/range/compareNode https://msdn.microsoft.com/library/ms536421(v=vs.85).aspx