Other functions

$type

$type(value) returns the type of value: "null", "number", "string", "boolean", "array", "object" or "function". It returns nothing for nothing.

[$type(1), $type("1"), $type(null), $type([]), $type({}), $type($type)]
=> ["number", "string", "null", "array", "object", "function"]

$type(missing)
=> undefined

$error

$error(message?) stops the evaluation with error D3137 and the given message.

bindings: {"limit": -1}
$limit >= 0 ? $limit : $error("The limit must not be negative")
=> error D3137

$assert

$assert(condition, message?) stops the evaluation with error D3141 and the message when condition is false. When it is true, it returns nothing.

input: address.json
($assert(Age >= 18, "Adults only"); FirstName)
=> "Fred"

input: address.json
($assert(Age >= 30, "Too young"); FirstName)
=> error D3141

$eval

$eval(expression, context?) parses and evaluates a JSONata expression given as a string. The context value is context if given, the current context otherwise. A syntax error in expression fails with D3120; an evaluation error, with D3121.

$eval("[1, $string(2), 3]")
=> [1, "2", 3]

input: address.json
$eval("FirstName & ' ' & Surname")
=> "Fred Smith"

$eval("a + b", {"a": 1, "b": 2})
=> 3

$clone

$clone(value) returns a deep copy of an object or array. Transforms use it to copy their input.

$clone({"a": [1, {"b": 2}]})
=> {"a": [1, {"b": 2}]}

Adapted from the JSONata documentation (MIT license).