var schema = require('boolean-json-schema')

The package exports a JSON Schema:

var ajv = new (require('ajv'))()
var assert = require('assert')

assert(ajv.validateSchema(schema))

You will need a compatible library, like Ajv, to validate objects:

var validBooleanJSON = ajv.compile(schema)

The simplest valid expression is just a variable name:

assert(validBooleanJSON('first'))

The syntax is very minimal. The schema permits negation, conjunction, disjunction, and arbitrary combinations:

assert(validBooleanJSON({not: 'x'}))

assert(validBooleanJSON({and: ['x', 'y']}))

assert(validBooleanJSON({or: ['x', 'y']}))

assert(validBooleanJSON({and: [{or: ['x', 'y']}, {not: 'z'}]}))

Conjunctions and disjunctions must have at least two operands:

assert(validBooleanJSON({and: ['x']}) === false)
assert(validBooleanJSON({and: ['x', 'y', 'z']}) === true)

assert(validBooleanJSON({or: ['x']}) === false)
assert(validBooleanJSON({or: ['x', 'y', 'z']}) === true)