Transform Each Item with jq map()

map(f) runs f on every element of an array and collects the results back into an array. It’s [.[] | f] with less typing.

Example input

[
  { "name": "Ada",   "price": 10 },
  { "name": "Linus", "price": 20 }
]

Pull one field from each

jq 'map(.name)' data.json     # ["Ada","Linus"]

Do math on each

jq 'map(.price * 1.1)' data.json     # [11, 22]

Reshape each object

jq 'map({ product: .name, withTax: (.price * 1.2) })' data.json

Output:

[
  { "product": "Ada", "withTax": 12 },
  { "product": "Linus", "withTax": 24 }
]

Add or change a field on each

jq 'map(.price += 5)' data.json          # bump every price by 5
jq 'map(. + { currency: "USD" })' data.json   # add a field to each object

map over object values with map_values()

For an object (not an array), use map_values(f) to transform each value, keeping keys:

{ "a": 1, "b": 2 }

jq 'map_values(. * 10)' obj.json     # {"a":10,"b":20}

map(f) = [.[] | f]. Use map for arrays and map_values for objects. Combine with select to filter-and-keep in one go: map(select(.price > 15)).