Using jq to combine multiple JSON files

To merge the .data elements of all the responses into the first response, you could run:

jq 'reduce inputs.data as $s (.; .data += $s)' page1.json page2.json ...

Alternatives

You could use the following filter in conjunction with the -n command-line option:

reduce inputs as $s (input; .data += ($s.data))

Or if you simply want an object of the form {"data": [ ... ]} then (again assuming you invoke jq with the -n command-line option) the following jq filter would suffice:

{data: [inputs.data] | add}

Just to provide closure, @peak provided the solution. I am using it in conjunction with the method found here for using wildcards in batch files to address multiple files. The code looks like this now:

set expanded_list=for /f "tokens=*" %%F in ('dir /b /a:-d "All Cards\!setname!_*.json"') do call set expanded_list=!expanded_list! "All Cards\%%F"jq-win32 "reduce inputs.data as $s (.; .data += $s)" !expanded_list! > "All Cards\!setname!.json"

All the individual pages for each card set are named "setname"_"pagenumber".json

The code finds all the pages for each set and combines them into one variable which I can pass into jq.

Thanks again!