{jsonview} shows a value as a JSON tree: every object and list is a <details> element that opens and closes on a click, with no script. Keys, strings, numbers, booleans and null each have their own colour, and a folded node says how many keys or items it holds.

The value comes from one of three places:

• the first parameter - a field holding an array (a page array, a row) or a text; the tag reads its items raw, as {debug} does, so a field that holds an array is that array. A text that reads as a JSON object or list is decoded.
• data= - a {data} store, a page array or a _data file by name.
• as a pair, the content - JSON taken as it stands, before the level walks it, so its braces need no {ignore}.

open= is the number of levels shown unfolded, 2 by default, and 0 folds everything. title= labels the outermost level.

Under the strict check these are errors: content that is no JSON, a second value, an unknown option (only open, title and data are read), a data= name that names nothing, an open= that is no number, and no value at all. The colours are --pad-jsonview-* custom properties.