> 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