What I Learned:

jq lets you select elements by starting with a . and accessing keys and arrays like it’s a JavaScript Object (which it is). This > feature uses the Object and Array index jq creates of a JSON document and look like this:

jq '.key[0].subkey[2:3].subsubkey'

jq programs can contain object constructors and array constructors. You use these when you want to wrap back up something you’ve pulled out of a JSON document using the above indexes:

jq '[{ key1: .key1, key2: .key2 }]'

jq contains built-in functions (length, sort, select, map) and pipes (|), and you can compose these together just like you can combine pipes and filters at the command line:

jq 'map({ order-of-magitude: .items | length | tostring | length })