FWIW, it is also possible to build the entire chart data msg inside the JSONata expression, without needing to build the structure around the data in another function node:
[{
"series": ["Field1"],
"labels": ["Field1"],
"data": $$.feeds.[{
"x": created_at,
"y": $number(field1)
}]
}]
Adrian, if you have not seen the JSONata "Tester" edit panel, it's hiding under the J: typed input editor panel -- pasting your msg data into the left-hand panel, you can see the chart data results immediately inside the right-hand panel...
