JQ examples: with entries

.

.name
.address.city

.["name"]
.address.["postal-code"]
.["address"].["postal-code"]

.car.options[1]
.[1]

.[10:]
.[10:15]
.[:15]

.{make, model}
.car.{make, model}

.{carMake: .make, carModel: .model}
//{"carMake": "mini cooper", "carModel": "countryman"}

.{car: (.make + .model)}
{car: (.make + " wroom!")}

.{(.make): .model}
//{"mini cooper": "countryman"}

.car.options[] | .price

jq '.people[] | select(.age > 30)'

jq '.people[] | sort_by(.age)'

jq '.people[] | group_by(.gender) | map({key: .[0].gender, value: map(.name)})'

jq '.people[].address[]'

jq --slurp 'reduce .[] as $item ({}; . * $item)'

.countries | map({name, id, people: .population})

map_values({name, ageYears: .age})

//input
{
    "john": "smith",
    "bob": "iger"
}
to_entries
// output
[
    {
      "key": "john",
      "value": "smith"
    },
    {
      "key": "bob",
      "value": "iger"
    }
  ]

//input
[
    {
        "key": "john",
        "value": "smith"
    },
    {
        "key": "bob",
        "value": "iger"
    }
]
//command
from_entries
//output
{
    "john": "smith",
    "bob": "iger"
}

with_entries(.key |= ("0"+.))

if .age > 30 then "old" else "young" end;

if .age > 30 then "old" elif .age > 20 then "middle" else "young" end;

def isOld: .age > 30;
{old: .age | isOld}