you can try

\doifnothing\currentstructurelabel{Do something}

It does not work in my case (even if the currenstructurelabel is empty it acts as if it not empty). In fact I asked that to get the following behaviour: — When there is a chapter label (\setuplabeltext[chapter=CHAPTER~]) I want that: CHAPTER ONE Cool CHAPTER 2 Cat CHAPTER 3 Mouse etc. — When there is no chapter label (\setuplabeltext[chapter=]) I want that: 1 Cool 2 Cat 3 Mouse etc. E.g.: \setuplabeltext[chapter=CHAPTER~] \define[1] \MyCommand{\doifelse{\currentsectioncountervalue}{1}{ONE}{#1}} \setuphead[chapter][deepnumbercommand=\MyCommand] \starttext \chapter{Cool} \chapter{Cat} \chapter{Mouse} \stoptext