Options

Regular options

• mode — 'default' by default in validator(), 'strong' by default in parser().
  See also strong mode documentation.

  'lax' mode disables some default schema coherence checks.

  'spec' mode is the same as 'lax' but also disables format assertion in draft2019-09 and newer $schema versions.

• useDefaults — false by default. Apply default: values from the schema to missing properties.

• removeAdditional — false by default.
  Removes additional properties instead of failing the validation on them.
  Supports additionalProperties: false and additionalItems: false.
  Note that it fails to compile the schema in case of uncertain paths with this option.

• includeErrors — false by default.
  Enable returning errors (without it, just a validaton flag is returned).

• allErrors — false by default.
  Return all errors, not just the first one.

• contentValidation — false by default for draft/2019-09 and newer,
  true by default for draft7 and older.
  Enables contentEncoding, contentMediaType, contentSchema usage for validation and makes
  failing those checks affect the boolean result of the validation.
  By default they are no-op per spec since draft/2019-09, and hence are treated as an unused
  keyword and raise an error at compile time unless allowUnusedKeywords option is enabled.

• dryRun — false by default.
  Don't produce a validator, just verify the schema and throw on first error.

• lint — false by default.
  Don't produce a validator, just verify the schema and collect all errors. Same as Linter mode.

• $schemaDefault — null by default.
  Can not be used if requireSchema is on.

• formatAssertion — true by default (false by default when mode = 'spec' and $schema is draft2019-09 or later).

  Switching it to false will disable format assertions, essentially making them not affect the result of validation at all, i.e. validation would pass regardless of all format strings in the schema.

  That (false) behaviour is specified as default in the upstream since draft2019-09, but not followed here, unless mode is set to 'spec', due to being potentially dangereous/unsafe and missing expected validation.

  For more info, see upstream documentation and upstream changelog.

• formats — {} by default.
  Additional formats to use.

• weakFormats — true in 'default' and 'lax'/'spec' modes, false in 'strong' mode by default.
  Add support for formats deemed potentially weak (currently, only RegExp).

• extraFormats — false by default.
  Enable extra built-in non-standard formats, see formats.js.

• schemas — empty by default.
  Either a Map, an Array, or an Object with schemas to resolve external $ref pointers.

Options for enforcing additional checks

All these options are false by default in 'default' and 'lax/'spec' modes and true by default in 'strong' mode.

• requireSchema — refuse to use schemas with missing $schema.

• requireValidation — refuse to use schemas which do not perform validation of all items or properties.

• requireStringValidation — refuse to use schemas which do not perform validation of all string properties against a format, pattern, or a contentSchema.

• complexityChecks — refuse to use schemas that might be missing required checks to avoid potential DoS, e.g. require maxLength on complex regexps and maxItems on complex uniqueItems. Note that it will pass if those are present but have a very high value, the only intent is to prevent a mistake when those checks are missed. If they are present, it is assumed that the shema author chose an appropriate value corresponding to the regex complexity.

• forbidNoopValues — refuse to compile schemas with certain noop keywords that make no sense.
  Currently, that is only $recursiveAnchor: false.
  This option is overridable even in 'strong' mode.

Options for relaxing coherence checks

• allowUnusedKeywords — opts.mode === 'lax' || opts.mode === 'spec' by default.
  Allows unused keywords to be present in the schema.

• allowUnreachable — opts.mode === 'lax' || opts.mode === 'spec' by default.
  Allows unreachable checks to be present in the schema.

Options to pass assumptions about input

If certain assumptions about input are always true, that information can be used to optimize the generated validator.

• unmodifiedPrototypes — false by default. Assume no mangled Object / Array prototypes in runtime.

• isJSON — false by default. Assume input to be JSON, which e.g. makes undefined impossible.