# Boolean Functions

> Standard JSONata Boolean functions available in expressions throughout the Fuuz platform. $boolean() Signature: $boolean(arg) Casts the argument to a…

Source: https://www.fuuz.com/help/boolean-functions
Last updated: 2026-06-16

How-To Guides · Expressions and scripting


Last updated June 16, 2026, 1:07 PM UTC

Standard JSONata Boolean functions available in expressions throughout the Fuuz platform.

## `$boolean()`

**Signature:** `$boolean(arg)`

Casts the argument to a Boolean using the following rules:

| Argument type | Result |
| --- | --- |
| Boolean | unchanged |
| string: empty | `false` |
| string: non-empty | `true` |
| number: 0 | `false` |
| number: non-zero | `true` |
| null | `false` |
| array: empty | `false` |
| array: contains a member that casts to `true` | `true` |
| array: all members cast to `false` | `false` |
| object: empty | `false` |
| object: non-empty | `true` |
| function | `false` |

## `$not()`

**Signature:** `$not(arg)`

Returns Boolean NOT on the argument. `arg` is first cast to a Boolean.

## `$exists()`

**Signature:** `$exists(arg)`

Returns Boolean `true` if the `arg` expression evaluates to a value, or `false` if the expression does not match anything (e.g. a path to a non-existent field reference).

## See Also

- [Boolean Operators](https://www.fuuz.com/help/boolean-operators)
- [Comparison Operators](https://www.fuuz.com/help/comparison-operators)
- [Aggregation Functions](https://www.fuuz.com/help/aggrigation-functions)
- [Array Functions](https://www.fuuz.com/help/array-functions)
- [Jsonata Tutorial](https://www.fuuz.com/help/jsonata-tutorial)

### Need more help?

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On this page

[$boolean()](#boolean)

[$not()](#not)

[$exists()](#exists)

[See Also](#see-also)