And in pathological cases where even this does not work (as I encountered a few days ago): 
\setbox\scratchbox=\vboxx{content}\ifdim\wd\scratchbox>\zeropoint .. \else .. \fi
dr. Hans van der Meer


> On 2 Aug 2021, at 17:17, Hans Hagen via ntg-context <ntg-context@ntg.nl> wrote:
> 
> On 8/2/2021 4:43 PM, Aditya Mahajan via ntg-context wrote:
>> On Mon, 2 Aug 2021, Benjamin Buchmuller via ntg-context wrote:
>>> Hi,
>>> 
>>> How can I check if a buffer or block has content (or is empty) before a \useblocks or \getbuffer statement?
>>> 
>>> I would like to typeset a headline only if the buffer/block has been used in a particular section and want to avoid headlines with empty sections.
>> There may be more efficient ways to do it (since buffers are stored at the lua end), but you can always do \doiftextelse(\getbuffer[...]} to test it buffer creates any output.
> indeed you know there is a way ...
> 
> \starttext
> 
> \startbuffer[test]
> test
> \stopbuffer
> 
> \doifelsebuffer{test} {YES} {NOP}
> 
> \permanent\protected\def\doifelsebuffercontent#1%
>  {\doifelse{\luaexpr{(string.strip(buffers.getcontent("#1")) ~= "" and "yes")}}{yes}}
> 
> \startbuffer[test]
> \stopbuffer
> 
> \doifelsebuffercontent{test} {YES} {NOP}
> 
> \startbuffer[test]
> 
> \stopbuffer
> 
> \doifelsebuffercontent{test} {YES} {NOP}
> 
> \stoptext
> 
> if we can agree on a proper name then i can add a (more efficient) \doifelse...
> 
> Hans
> 
> 
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>                                          Hans Hagen | PRAGMA ADE
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