const ajv = new Ajv({processCode: transpileFunc})
const validate = ajv.compile(schema) // transpiled es7 async function
validate(data).then(successFunc).catch(errorFunc)

const ajv = new Ajv({ allErrors: true })
const validate = ajv.compile(schema.valueOf())
let user = {}
let valid = validate(user)
console.log({ valid }) //=> {valid: false}
console.log(validate.errors) //=> {valid: false}

ajv.addKeyword({
  keyword: "range",
  type: "number",
  compile([min, max], parentSchema) {
    return parentSchema.exclusiveRange === true
      ? (data) => data > min && data < max
      : (data) => data >= min && data <= max
  },
  errors: false,
  metaSchema: {
    // schema to validate keyword value
    type: "array",
    items: [{type: "number"}, {type: "number"}],
    minItems: 2,
    additionalItems: false,
  },
})

const schema = {
  range: [2, 4],
  exclusiveRange: true,
}
const validate = ajv.compile(schema)
console.log(validate(2.01)) // true
console.log(validate(3.99)) // true
console.log(validate(2)) // false
console.log(validate(4)) // false

const userValidator = compile( userSchema );
userValidator( data );
// { ok: true } or
// { ok: false, errors: [Ajv errors...], explanation: string }

ajv.addKeyword({
  keyword: "range",
  type: "number",
  schemaType: "array",
  implements: "exclusiveRange",
  compile: ([min, max], parentSchema) =>
    parentSchema.exclusiveRange === true
      ? (data) => data > min && data < max
      : (data) => data >= min && data <= max,
})

const schema = {range: [2, 4], exclusiveRange: true}
const validate = ajv.compile(schema)
console.log(validate(2.01)) // true
console.log(validate(3.99)) // true
console.log(validate(2)) // false
console.log(validate(4)) // false