One of the fastest JSON Schema validators for node.js. It uses [doT templates](https://github.com/olado/doT) to generate super-fast validating functions.
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.
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.
- _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.
- _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.