ajv passes all the tests from [JSON Schema Test Suite](https://github.com/json-schema/JSON-Schema-Test-Suite) (apart from the one that requires that `1.0` is not an integer).
Benchmark of the test suite - [json-schema-benchmark](https://github.com/ebdrup/json-schema-benchmark).
[Same benchmark](https://github.com/epoberezkin/json-schema-benchmark) run on faster CPU with node 0.12.
[Benchmark of individual test cases](https://rawgit.com/zaggino/z-schema/master/benchmark/results.html) by [z-schema](https://github.com/zaggino/z-schema).
ajv compiles schemas to functions and caches them in all cases (using stringified schema as a key - using [json-stable-stringify](https://github.com/substack/json-stable-stringify)), so that the next time the same schema is used (not necessarily the same object instance) it won't be compiled again.
Validating function returns boolean and has properties `errors` with the errors from the last validation (`null` if there were no errors) and `schema` with the reference to the original schema.
Unless options `validateSchema` is false, the schema will be validated against meta-schema and if schema is invalid the errors will be logged. See [options](#options).
Instead of the schema you can use the key that was previously passed to `addSchema`, the schema id if it was present in the schema or any previously resolved reference.
Add and compile schema(s). It does the same as `.compile` with two differences:
- array of schemas can be passed (schemas should have ids), the second parameter will be ignored.
- key can be passed that can be used to reference the schema and will be used as the schema id if there is no id inside the schema. If the key is not passed, the schema id will be used as the key.
Once the schema added it and all the references inside it can be referenced in other schemas and used to validate data.
In the current version all the referenced schemas should be added before the schema that uses them is compiled, so the circular references are not supported.
By default schema is validated against meta-schema before it is compiled and if the schema does not pass validation the exception is thrown. This behaviour is controlled by `validateSchema` option.
Validates schema. This method should be used to validate schemas rather than `validate` due to the inconsistency of `uri` format in JSON-Schema standart.
By default this method is called automatically when the schema is added, so you rarely need to use it directly.
Retrieve compiled schema previously added with `addSchema` by the key passed to `addSchema` or by its full reference (id). Returned validating function has `schema` property with the reference to the original schema.
Remove added/cached schema. Even if schema is referenced by other schemas it can be safely removed as dependent schemas have local references.
Schema can be removed using key passed to `addSchema`, it's full reference (id) or using actual schema object that will be stable-stringified to remove schema from cache.
- _format_: formats validation mode ('fast' by default). Pass 'full' for more correct and slow validation or `false` not to validate formats at all. E.g., 25:00:00 and 2015/14/33 will be invalid time and date in 'full' mode but it will be valid in 'fast' mode.
- _schemas_: an array or object of schemas that will be added to the instance. If the order is important, pass array. In this case schemas must have IDs in them. Otherwise the object can be passed - `addSchema(value, key)` will be called for each schema in this object.
- _validateSchema_: validate added/compiled schemas against meta-schema (true by default). `$schema` property in the schema can either be absent (draft-4 meta-schema will be used) or can be a reference to any previously added schema. If the validation fails, the exception is thrown. Pass "log" in this option to log error instead of throwing exception. Pass `false` to skip schema validation.
- _missingRefs_: by default if the reference cannot be resolved during compilation the exception is thrown. Pass 'ignore' to log error during compilation and pass validation. Pass 'fail' to log error and successfully compile schema but fail validation if this rule is checked.
- _unicode_: calculate correct length of strings with unicode pairs (true by default). Pass `false` to use `.length` of strings that is faster, but gives "incorrect" lengths of strings with unicode pairs - each unicode pair is counted as two characters.
- _beautify_: format the generated function with [js-beautify](https://github.com/beautify-web/js-beautify) (the validating function is generated without line-breaks). `npm install js-beautify` to use this option. `true` or js-beautify options can be passed.
- _cache_: an optional instance of cache to store compiled schemas using stable-stringified schema as a key. For example, set-associative cache [sacjs](https://github.com/epoberezkin/sacjs) can be used. If not passed then a simple hash is used which is good enough for the common use case (a limited number of statically defined schemas). Cache should have methods `put(key, value)` and `get(key)`.
