TypeBox

JSON Schema Type Builder with Static Type Resolution for TypeScript

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## Install

Node

```bash
$ npm install @sinclair/typebox --save
```

Deno and ESM

```typescript
import { Static, Type } from 'https://esm.sh/@sinclair/typebox'
```

## Example

```typescript
import { Static, Type } from '@sinclair/typebox'

const T = Type.String()     // const T = { type: 'string' }

type T = Static<typeof T>   // type T = string
```


## Overview

TypeBox is a type builder library that creates in-memory JSON Schema objects that can be statically inferred as TypeScript types. The schemas produced by this library are designed to match the static type checking rules of the TypeScript compiler. TypeBox enables one to create a unified type that can be statically checked by TypeScript and runtime asserted using standard JSON Schema validation.

TypeBox is designed to enable JSON schema to compose with the same flexibility as TypeScript's type system. It can be used either as a simple tool to build up complex schemas or integrated into REST and RPC services to help validate data received over the wire. 

License MIT

## Contents
- [Install](#install)
- [Overview](#overview)
- [Usage](#usage)
- [Types](#types)
  - [Standard](#types-standard)
  - [Modifiers](#types-modifiers)
  - [Options](#types-options)
  - [Extended](#types-extended)
  - [Reference](#types-reference)
  - [Recursive](#types-recursive)
  - [Generic](#types-generic)
  - [Conditional](#types-conditional)
  - [Unsafe](#types-unsafe)
  - [Guards](#types-guards)
  - [Strict](#types-strict)
- [Values](#values)
  - [Create](#values-create)
  - [Clone](#values-clone)
  - [Check](#values-check)
  - [Cast](#values-cast)
  - [Equal](#values-equal)
  - [Diff](#values-diff)
  - [Patch](#values-patch)
  - [Errors](#values-errors)
  - [Pointer](#values-pointer)
- [TypeCheck](#typecheck)
  - [Ajv](#typecheck-ajv)
  - [Compiler](#typecheck-compiler)
  - [Formats](#typecheck-formats)
- [Benchmark](#benchmark)
  - [Compile](#benchmark-compile)
  - [Validate](#benchmark-validate)
  - [Compression](#benchmark-compression)
- [Contribute](#contribute)

## Usage

The following demonstrates TypeBox's general usage.

```typescript

import { Static, Type } from '@sinclair/typebox'

//--------------------------------------------------------------------------------------------
//
// Let's say you have the following type ...
//
//--------------------------------------------------------------------------------------------

type T = {
  id: string,
  name: string,
  timestamp: number
}

//--------------------------------------------------------------------------------------------
//
// ... you can express this type in the following way.
//
//--------------------------------------------------------------------------------------------

const T = Type.Object({                              // const T = {
  id: Type.String(),                                 //   type: 'object',
  name: Type.String(),                               //   properties: { 
  timestamp: Type.Integer()                          //     id: { 
})                                                   //       type: 'string' 
                                                     //     },
                                                     //     name: { 
                                                     //       type: 'string' 
                                                     //     },
                                                     //     timestamp: { 
                                                     //       type: 'integer' 
                                                     //     }
                                                     //   }, 
                                                     //   required: [
                                                     //     'id',
                                                     //     'name',
                                                     //     'timestamp'
                                                     //   ]
                                                     // } 

//--------------------------------------------------------------------------------------------
//
// ... then infer back to the original static type this way.
//
//--------------------------------------------------------------------------------------------

type T = Static<typeof T>                            // type T = {
                                                     //   id: string,
                                                     //   name: string,
                                                     //   timestamp: number
                                                     // }

//--------------------------------------------------------------------------------------------
//
// ... then use the type both as JSON schema and as a TypeScript type.
//
//--------------------------------------------------------------------------------------------

function receive(value: T) {                         // ... as a Type

  if(JSON.validate(T, value)) {                      // ... as a Schema
  
    // ok...
  }
}
```


## Types

TypeBox provides a set of functions that allow you to compose JSON Schema similar to how you would compose static types with TypeScript. Each function creates a JSON schema fragment which can compose into more complex types. The schemas produced by TypeBox can be passed directly to any JSON Schema compliant validator, or used to reflect runtime metadata for a type.

### Standard

The following table lists the standard TypeBox types.

```typescript
┌────────────────────────────────┬─────────────────────────────┬────────────────────────────────┐
│ TypeBox                        │ TypeScript                  │ JSON Schema                    │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Any()           │ type T = any                │ const T = { }                  │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Unknown()       │ type T = unknown            │ const T = { }                  │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.String()        │ type T = string             │ const T = {                    │
│                                │                             │   type: 'string'               │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Number()        │ type T = number             │ const T = {                    │
│                                │                             │   type: 'number'               │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Integer()       │ type T = number             │ const T = {                    │
│                                │                             │   type: 'integer'              │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Boolean()       │ type T = boolean            │ const T = {                    │
│                                │                             │   type: 'boolean'              │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Null()          │ type T = null               │ const T = {                    │
│                                │                             │    type: 'null'                │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.RegEx(/foo/)    │ type T = string             │ const T = {                    │
│                                │                             │    type: 'string',             │
│                                │                             │    pattern: 'foo'              │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Literal(42)     │ type T = 42                 │ const T = {                    │
│                                │                             │    const: 42,                  │
│                                │                             │    type: 'number'              │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Array(          │ type T = number[]           │ const T = {                    │
│   Type.Number()                │                             │   type: 'array',               │
│ )                              │                             │   items: {                     │
│                                │                             │     type: 'number'             │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Object({        │ type T = {                  │ const T = {                    │
│   x: Type.Number(),            │   x: number,                │   type: 'object',              │
│   y: Type.Number()             │   y: number                 │   properties: {                │
│ })                             │ }                           │      x: {                      │
│                                │                             │        type: 'number'          │
│                                │                             │      },                        │
│                                │                             │      y: {                      │
│                                │                             │        type: 'number'          │
│                                │                             │      }                         │
│                                │                             │   },                           │
│                                │                             │   required: ['x', 'y']         │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Tuple([         │ type T = [number, number]   │ const T = {                    │
│   Type.Number(),               │                             │   type: 'array',               │
│   Type.Number()                │                             │   items: [{                    │
│ ])                             │                             │      type: 'number'            │
│                                │                             │    }, {                        │
│                                │                             │      type: 'number'            │
│                                │                             │    }],                         │
│                                │                             │    additionalItems: false,     │
│                                │                             │    minItems: 2,                │
│                                │                             │    maxItems: 2                 │
│                                │                             │ }                              │
│                                │                             │                                │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ enum Foo {                     │ enum Foo {                  │ const T = {                    │
│   A,                           │   A,                        │   anyOf: [{                    │
│   B                            │   B                         │     type: 'number',            │
│ }                              │ }                           │     const: 0                   │
│                                │                             │   }, {                         │
│ const T = Type.Enum(Foo)       │ type T = Foo                │     type: 'number',            │
│                                │                             │     const: 1                   │
│                                │                             │   }]                           │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.KeyOf(          │ type T = keyof {            │ const T = {                    │
│   Type.Object({                │   x: number,                │   anyOf: [{                    │
│     x: Type.Number(),          │   y: number                 │     type: 'string',            │
│     y: Type.Number()           │ }                           │     const: 'x'                 │
│   })                           │                             │   }, {                         │
│ )                              │                             │     type: 'string',            │
│                                │                             │     const: 'y'                 │
│                                │                             │   }]                           │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Union([         │ type T = string | number    │ const T = {                    │
│   Type.String(),               │                             │   anyOf: [{                    │
│   Type.Number()                │                             │      type: 'string'            │
│ ])                             │                             │   }, {                         │
│                                │                             │      type: 'number'            │
│                                │                             │   }]                           │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Intersect([     │ type T = {                  │ const T = {                    │
│   Type.Object({                │   x: number                 │   type: 'object',              │
│     x: Type.Number()           │ } & {                       │   properties: {                │
│   }),                          │   y: number                 │     x: {                       │
│   Type.Object({                │ }                           │       type: 'number'           │
│     y: Type.Number()           │                             │     },                         │
│   })                           │                             │     y: {                       │
│ ])                             │                             │       type: 'number'           │
│                                │                             │     }                          │
│                                │                             │   },                           │
│                                │                             │   required: ['x', 'y']         │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Never()         │ type T = never              │ const T = {                    │
│                                │                             │   allOf: [{                    │
│                                │                             │     type: 'boolean',           │
│                                │                             │     const: false               │
│                                │                             │   }, {                         │
│                                │                             │     type: 'boolean',           │
│                                │                             │     const: true                │
│                                │                             │   }]                           │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Record(         │ type T = Record<            │ const T = {                    │
│   Type.String(),               │   string,                   │   type: 'object',              │
│   Type.Number()                │   number,                   │   patternProperties: {         │
│ )                              │ >                           │     '^.*$': {                  │
│                                │                             │       type: 'number'           │
│                                │                             │     }                          │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Partial(        │ type T = Partial<{          │ const T = {                    │
│   Type.Object({                │   x: number,                │   type: 'object',              │
│     x: Type.Number(),          │   y: number                 │   properties: {                │
│     y: Type.Number()           | }>                          │     x: {                       │
│   })                           │                             │       type: 'number'           │
│ )                              │                             │     },                         │
│                                │                             │     y: {                       │
│                                │                             │       type: 'number'           │
│                                │                             │     }                          │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Required(       │ type T = Required<{         │ const T = {                    │
│   Type.Object({                │   x?: number,               │   type: 'object',              │
│     x: Type.Optional(          │   y?: number                │   properties: {                │
│       Type.Number()            | }>                          │     x: {                       │
│     ),                         │                             │       type: 'number'           │
│     y: Type.Optional(          │                             │     },                         │
│       Type.Number()            │                             │     y: {                       │
│     )                          │                             │       type: 'number'           │
│   })                           │                             │     }                          │
│ )                              │                             │   },                           │
│                                │                             │   required: ['x', 'y']         │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Pick(           │ type T = Pick<{             │ const T = {                    │
│   Type.Object({                │   x: number,                │   type: 'object',              │
│     x: Type.Number(),          │   y: number                 │   properties: {                │
│     y: Type.Number()           | }, 'x'>                     │     x: {                       │
│   }), ['x']                    │                             │       type: 'number'           │
│ )                              │                             │     }                          │
│                                │                             │   },                           │
│                                │                             │   required: ['x']              │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Omit(           │ type T = Omit<{             │ const T = {                    │
│   Type.Object({                │   x: number,                │   type: 'object',              │
│     x: Type.Number(),          │   y: number                 │   properties: {                │
│     y: Type.Number()           | }, 'x'>                     │     y: {                       │
│   }), ['x']                    │                             │       type: 'number'           │
│ )                              │                             │     }                          │
│                                │                             │   },                           │
│                                │                             │   required: ['y']              │
│                                │                             │ }                              │
│                                │                             │                                │
└────────────────────────────────┴─────────────────────────────┴────────────────────────────────┘
```


### Modifiers

TypeBox provides modifiers that can be applied to an objects properties. This allows for `optional` and `readonly` to be applied to that property. The following table illustates how they map between TypeScript and JSON Schema.

```typescript
┌────────────────────────────────┬─────────────────────────────┬────────────────────────────────┐
│ TypeBox                        │ TypeScript                  │ JSON Schema                    │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Object({        │ type T = {                  │ const T = {                    │
│   name: Type.Optional(         │   name?: string             │   type: 'object',              │
│     Type.String()              │ }                           │   properties: {                │
│   )                            │                             │      name: {                   │
│ })  	                         │                             │        type: 'string'          │
│                                │                             │      }                         │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Object({        │ type T = {                  │ const T = {                    │
│   name: Type.Readonly(         │   readonly name: string     │   type: 'object',              │
│     Type.String()              │ }                           │   properties: {                │
│   )                            │                             │     name: {                    │
│ })  	                         │                             │       type: 'string'           │
│                                │                             │     }                          │
│                                │                             │   },                           │
│                                │                             │   required: ['name']           │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Object({        │ type T = {                  │ const T = {                    │
│   name: Type.ReadonlyOptional( │   readonly name?: string    │   type: 'object',              │
│     Type.String()              │ }                           │   properties: {                │
│   )                            │                             │     name: {                    │
│ })  	                         │                             │       type: 'string'           │
│                                │                             │     }                          │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
└────────────────────────────────┴─────────────────────────────┴────────────────────────────────┘
```


### Options

You can pass additional JSON schema options on the last argument of any given type. The following are some examples.

```typescript
// string must be an email
const T = Type.String({ format: 'email' })

// number must be a multiple of 2
const T = Type.Number({ multipleOf: 2 })

// array must have at least 5 integer values
const T = Type.Array(Type.Integer(), { minItems: 5 })
```


### Extended

In addition to JSON schema types, TypeBox provides several extended types that allow for the composition of `function` and `constructor` types. These additional types are not valid JSON Schema and will not validate using typical JSON Schema validation. However, these types can be used to frame JSON schema and describe callable interfaces that may receive JSON validated data. These types are as follows.

```typescript
┌────────────────────────────────┬─────────────────────────────┬────────────────────────────────┐
│ TypeBox                        │ TypeScript                  │ Extended Schema                │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Constructor([   │ type T = new (              │ const T = {                    │
│   Type.String(),               │  arg0: string,              │   type: 'constructor'          │
│   Type.Number()                │  arg1: number               │   parameters: [{               │
│ ], Type.Boolean())             │ ) => boolean                │     type: 'string'             │
│                                │                             │   }, {                         │
│                                │                             │     type: 'number'             │
│                                │                             │   }],                          │
│                                │                             │   return: {                    │
│                                │                             │     type: 'boolean'            │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Function([      │ type T = (                  │ const T = {                    │
|   Type.String(),               │  arg0: string,              │   type : 'function',           │
│   Type.Number()                │  arg1: number               │   parameters: [{               │
│ ], Type.Boolean())             │ ) => boolean                │     type: 'string'             │
│                                │                             │   }, {                         │
│                                │                             │     type: 'number'             │
│                                │                             │   }],                          │
│                                │                             │   return: {                    │
│                                │                             │     type: 'boolean'            │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Uint8Array()    │ type T = Uint8Array         │ const T = {                    │
│                                │                             │   type: 'object',              │
│                                │                             │   specialized: 'Uint8Array'    │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Promise(        │ type T = Promise<string>    │ const T = {                    │
│   Type.String()                │                             │   type: 'promise',             │
│ )                              │                             │   item: {                      │
│                                │                             │     type: 'string'             │
│                                │                             │   }                            │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Undefined()     │ type T = undefined          │ const T = {                    │
│                                │                             │   type: 'object',              │
│                                │                             │   specialized: 'Undefined'     │
│                                │                             │ }                              │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Type.Void()          │ type T = void               │ const T = {                    │
│                                │                             │   type: 'null'                 │
│                                │                             │ }                              │
│                                │                             │                                │
└────────────────────────────────┴─────────────────────────────┴────────────────────────────────┘
```


### Reference

Use `Type.Ref(...)` to create referenced types. The target type must specify an `$id`.

```typescript
const T = Type.String({ $id: 'T' })                  // const T = {
                                                     //    $id: 'T',
                                                     //    type: 'string'
                                                     // }
                                             
const R = Type.Ref(T)                                // const R = {
                                                     //    $ref: 'T'
                                                     // }
```


### Recursive

Use `Type.Recursive(...)` to create recursive types.

```typescript
const Node = Type.Recursive(Node => Type.Object({    // const Node = {
  id: Type.String(),                                 //   $id: 'Node',
  nodes: Type.Array(Node)                            //   type: 'object',
}), { $id: 'Node' })                                 //   properties: {
                                                     //     id: {
                                                     //       type: 'string'
                                                     //     },
                                                     //     nodes: {
                                                     //       type: 'array',
                                                     //       items: {
                                                     //         $ref: 'Node'
                                                     //       }
                                                     //     }
                                                     //   },
                                                     //   required: [
                                                     //     'id',
                                                     //     'nodes'
                                                     //   ]
                                                     // }

type Node = Static<typeof Node>                      // type Node = {
                                                     //   id: string
                                                     //   nodes: Node[]
                                                     // }

function test(node: Node) {
  const id = node.nodes[0].nodes[0]                  // id is string
                 .nodes[0].nodes[0]
                 .id
}
```


### Generic

Use functions to create generic types. The following creates a generic `Nullable<T>` type. 

```typescript
import { Type, Static, TSchema } from '@sinclair/typebox'

const Nullable = <T extends TSchema>(type: T) => Type.Union([type, Type.Null()])

const T = Nullable(Type.String())                    // const T = {
                                                     //   anyOf: [{
                                                     //     type: 'string'
                                                     //   }, {
                                                     //     type: 'null'
                                                     //   }]
                                                     // }

type T = Static<typeof T>                            // type T = string | null

const U = Nullable(Type.Number())                    // const U = {
                                                     //   anyOf: [{
                                                     //     type: 'number'
                                                     //   }, {
                                                     //     type: 'null'
                                                     //   }]
                                                     // }

type U = Static<typeof U>                            // type U = number | null
```


### Conditional

Use the conditional module to create [Conditional Types](https://www.typescriptlang.org/docs/handbook/2/conditional-types.html). This module implements TypeScript's structural equivalence checks to enable TypeBox types to be conditionally inferred at runtime. This module also provides the [Extract](https://www.typescriptlang.org/docs/handbook/utility-types.html#extracttype-union) and [Exclude](https://www.typescriptlang.org/docs/handbook/utility-types.html#excludeuniontype-excludedmembers) utility types which are expressed as conditional types in TypeScript. 

The conditional module is provided as an optional import.

```typescript
import { Conditional } from '@sinclair/typebox/conditional'
```
The following table shows the TypeBox mappings between TypeScript and JSON schema.

```typescript
┌────────────────────────────────┬─────────────────────────────┬────────────────────────────────┐
│ TypeBox                        │ TypeScript                  │ JSON Schema                    │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Conditional.Extends( │ type T =                    │ const T = {                    │
│   Type.String(),               │  string extends number      │   const: false,                │
│   Type.Number(),               │  true : false               │   type: 'boolean'              │
│   Type.Literal(true),          │                             │ }                              │
│   Type.Literal(false)          │                             │                                │
│ )                              │                             │                                │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Conditional.Extract( │ type T = Extract<           │ const T = {                    │
│   Type.Union([                 │   'a' | 'b' | 'c',          │   anyOf: [{                    │
│     Type.Literal('a'),         │   'a' | 'f'                 │     const: 'a'                 │
│     Type.Literal('b'),         │ >                           │     type: 'string'             │
│     Type.Literal('c')          │                             │   }]                           │
│   ]),                          │                             │ }                              │
│   Type.Union([                 │                             │                                │
│     Type.Literal('a'),         │                             │                                │
│     Type.Literal('f')          │                             │                                │
│   ])                           │                             │                                │
│ )                              │                             │                                │
│                                │                             │                                │
├────────────────────────────────┼─────────────────────────────┼────────────────────────────────┤
│ const T = Conditional.Exclude( │ type T = Exclude<           │ const T = {                    │
│   Type.Union([                 │   'a' | 'b' | 'c',          │   anyOf: [{                    │
│     Type.Literal('a'),         │   'a'                       │     const: 'b',                │
│     Type.Literal('b'),         │ >                           │     type: 'string'             │
│     Type.Literal('c')          │                             │   }, {                         │
│   ]),                          │                             │     const: 'c',                │
│   Type.Union([                 │                             │     type: 'string'             │
│     Type.Literal('a')          │                             │   }]                           │
│   ])                           │                             │ }                              │
│ )                              │                             │                                │
│                                │                             │                                │
└────────────────────────────────┴─────────────────────────────┴────────────────────────────────┘
```


### Unsafe

Use `Type.Unsafe(...)` to create custom schemas with user defined inference rules.

```typescript
const T = Type.Unsafe<string>({ type: 'number' })    // const T = {
                                                     //   type: 'number'
                                                     // }

type T = Static<typeof T>                            // type T = string
```

This function can be used to create custom schemas for validators that require specific schema representations. An example of this might be OpenAPI's `nullable` and `enum` schemas which are not provided by TypeBox. The following demonstrates using `Type.Unsafe(...)` to create these types.

```typescript
import { Type, Static, TSchema } from '@sinclair/typebox'

//--------------------------------------------------------------------------------------------
//
// Nullable<T>
//
//--------------------------------------------------------------------------------------------

function Nullable<T extends TSchema>(schema: T) {
  return Type.Unsafe<Static<T> | null>({ ...schema, nullable: true })
}

const T = Nullable(Type.String())                    // const T = {
                                                     //   type: 'string',
                                                     //   nullable: true
                                                     // }

type T = Static<typeof T>                            // type T = string | null


//--------------------------------------------------------------------------------------------
//
// StringEnum<string[]>
//
//--------------------------------------------------------------------------------------------

function StringEnum<T extends string[]>(values: [...T]) {
  return Type.Unsafe<T[number]>({ type: 'string', enum: values })
}

const T = StringEnum(['A', 'B', 'C'])                // const T = {
                                                     //   enum: ['A', 'B', 'C']
                                                     // }

type T = Static<typeof T>                            // type T = 'A' | 'B' | 'C'
```


### Guards

Use the guard module to test if values are TypeBox types.

```typescript
import { TypeGuard } from '@sinclair/typebox/guard'

const T = Type.String()

if(TypeGuard.TString(T)) {
    
  // T is TString
}
```


### Strict

TypeBox schemas contain the `Kind` and `Modifier` symbol properties. These properties are provided to enable runtime type reflection on schemas, as well as helping TypeBox internally compose types. These properties are not strictly valid JSON schema; so in some cases it may be desirable to omit them. TypeBox provides a `Type.Strict()` function that will omit these properties if necessary.

```typescript
const T = Type.Object({                              // const T = {
  name: Type.Optional(Type.String())                 //   [Kind]: 'Object',
})                                                   //   type: 'object',
                                                     //   properties: {
                                                     //     name: {
                                                     //       [Kind]: 'String',
                                                     //       type: 'string',
                                                     //       [Modifier]: 'Optional'
                                                     //     }
                                                     //   }
                                                     // }

const U = Type.Strict(T)                             // const U = {
                                                     //   type: 'object', 
                                                     //   properties: { 
                                                     //     name: { 
                                                     //       type: 'string' 
                                                     //     } 
                                                     //   } 
                                                     // }
```


## Values

TypeBox includes an optional values module that can be used to perform common operations on JavaScript values. This module enables one to create, check and cast values from types. It also provides functionality to check equality, clone and diff and patch JavaScript values. The value module is provided as an optional import.

```typescript
import { Value } from '@sinclair/typebox/value'
```


### Create

Use the Create function to create a value from a TypeBox type. TypeBox will use default values if specified.

```typescript
const T = Type.Object({ x: Type.Number(), y: Type.Number({ default: 42 }) })

const A = Value.Create(T)                            // const A = { x: 0, y: 42 }
```


### Clone

Use the Clone function to deeply clone a value

```typescript
const A = Value.Clone({ x: 1, y: 2, z: 3 })          // const A = { x: 1, y: 2, z: 3 }
```


### Check

Use the Check function to type check a value

```typescript
const T = Type.Object({ x: Type.Number() })

const R = Value.Check(T, { x: 1 })                   // const R = true
```


### Cast

Use the Cast function to cast a value into a type. The cast function will retain as much information as possible from the original value.

```typescript
const T = Type.Object({ x: Type.Number(), y: Type.Number() }, { additionalProperties: false })

const X = Value.Cast(T, null)                        // const X = { x: 0, y: 0 }

const Y = Value.Cast(T, { x: 1 })                    // const Y = { x: 1, y: 0 }

const Z = Value.Cast(T, { x: 1, y: 2, z: 3 })        // const Z = { x: 1, y: 2 }
```


### Equal

Use the Equal function to deeply check for value equality.

```typescript
const R = Value.Equal(                               // const R = true
  { x: 1, y: 2, z: 3 },
  { x: 1, y: 2, z: 3 }
)
```


### Diff

Use the Diff function to produce a sequence of edits to transform one value into another.

```typescript
const E = Value.Diff<any>(                          // const E = [
  { x: 1, y: 2, z: 3 },                             //   { type: 'update', path: '/y', value: 4 },
  { y: 4, z: 5, w: 6 }                              //   { type: 'update', path: '/z', value: 5 },
)                                                   //   { type: 'insert', path: '/w', value: 6 },
                                                    //   { type: 'delete', path: '/x' }
                                                    // ]
```


### Patch

Use the Patch function to apply edits

```typescript
const A = { x: 1, y: 2 }

const B = { x: 3 }

const E = Value.Diff<any>(A, B)                      // const E = [
                                                     //   { type: 'update', path: '/x', value: 3 },
                                                     //   { type: 'delete', path: '/y' }
                                                     // ]

const C = Value.Patch<any>(A, E)                     // const C = { x: 3 }
```


### Errors

Use the Errors function enumerate validation errors.

```typescript
const T = Type.Object({ x: Type.Number(), y: Type.Number() })

const R = [...Value.Errors(T, { x: '42' })]          // const R = [{
                                                     //   schema: { type: 'number' },
                                                     //   path: '/x',
                                                     //   value: '42',
                                                     //   message: 'Expected number'
                                                     // }, {
                                                     //   schema: { type: 'number' },
                                                     //   path: '/y',
                                                     //   value: undefined,
                                                     //   message: 'Expected number'
                                                     // }]
```


### Pointer

Use ValuePointer to perform mutable updates on existing values using [RFC6901](https://www.rfc-editor.org/rfc/rfc6901) Json Pointers.

```typescript
import { ValuePointer } from '@sinclair/typebox/value'

const A = { x: 0, y: 0, z: 0 }

ValuePointer.Set(A, '/x', 1)                         // const A = { x: 1, y: 0, z: 0 }
ValuePointer.Set(A, '/y', 1)                         // const A = { x: 1, y: 1, z: 0 }
ValuePointer.Set(A, '/z', 1)                         // const A = { x: 1, y: 1, z: 1 }
```


## TypeCheck

TypeBox is written to target JSON Schema Draft 6 and can be used with any Draft 6 compliant validator. TypeBox is developed and tested against Ajv and can be used in any application already making use of this validator. Additionally, TypeBox also provides an optional type compiler that can be used to attain improved compilation and validation performance for certain application types.

### Ajv

The following example shows setting up Ajv to work with TypeBox. 

```bash
$ npm install ajv ajv-formats --save
```

```typescript
import { Type }   from '@sinclair/typebox'
import addFormats from 'ajv-formats'
import Ajv        from 'ajv'

//--------------------------------------------------------------------------------------------
//
// Setup Ajv validator with the following options and formats
//
//--------------------------------------------------------------------------------------------

const ajv = addFormats(new Ajv({}), [
  'date-time', 
  'time', 
  'date', 
  'email',  
  'hostname', 
  'ipv4', 
  'ipv6', 
  'uri', 
  'uri-reference', 
  'uuid',
  'uri-template', 
  'json-pointer', 
  'relative-json-pointer', 
  'regex'
])

//--------------------------------------------------------------------------------------------
//
// Create a TypeBox type
//
//--------------------------------------------------------------------------------------------

const T = Type.Object({
  x: Type.Number(),
  y: Type.Number(),
  z: Type.Number()
})

//--------------------------------------------------------------------------------------------
//
// Validate Data
//
//--------------------------------------------------------------------------------------------

const R = ajv.validate(T, { x: 1, y: 2, z: 3 })      // const R = true
```


### Compiler

TypeBox provides an optional high performance just-in-time (JIT) compiler and type checker that can be used in applications that require extremely fast validation. Note that this compiler is optimized for TypeBox types only where the schematics are known in advance. If defining custom types with `Type.Unsafe<T>` please consider Ajv.

The compiler module is provided as an optional import.

```typescript
import { TypeCompiler } from '@sinclair/typebox/compiler'
```

Use the `Compile(...)` function to compile a type.

```typescript
const C = TypeCompiler.Compile(Type.Object({         // const C: TypeCheck<TObject<{
  x: Type.Number(),                                  //     x: TNumber;
  y: Type.Number(),                                  //     y: TNumber;
  z: Type.Number()                                   //     z: TNumber;
}))                                                  // }>>

const R = C.Check({ x: 1, y: 2, z: 3 })              // const R = true
```

Validation errors can be read with the `Errors(...)` function.

```typescript
const C = TypeCompiler.Compile(Type.Object({         // const C: TypeCheck<TObject<{
  x: Type.Number(),                                  //     x: TNumber;
  y: Type.Number(),                                  //     y: TNumber;
  z: Type.Number()                                   //     z: TNumber;
}))                                                  // }>>

const value = { }

const errors = [...C.Errors(value)]                  // const errors = [{
                                                     //   schema: { type: 'number' },
                                                     //   path: '/x',
                                                     //   value: undefined,
                                                     //   message: 'Expected number'
                                                     // }, {
                                                     //   schema: { type: 'number' },
                                                     //   path: '/y',
                                                     //   value: undefined,
                                                     //   message: 'Expected number'
                                                     // }, {
                                                     //   schema: { type: 'number' },
                                                     //   path: '/z',
                                                     //   value: undefined,
                                                     //   message: 'Expected number'
                                                     // }]
```

Compiled routines can be inspected with the `.Code()` function.

```typescript
const C = TypeCompiler.Compile(Type.String())        // const C: TypeCheck<TString>

console.log(C.Code())                                // return function check(value) {
                                                     //   return (
                                                     //     (typeof value === 'string')
                                                     //   )
                                                     // }
```


### Formats

Use the format module to create user defined string formats. The format module is used by the Value and TypeCompiler modules only. If using Ajv, please refer to the official Ajv format documentation located [here](https://ajv.js.org/guide/formats.html).

The format module is an optional import.

```typescript
import { Format } from '@sinclair/typebox/format'
```

The following creates a `palindrome` string format.

```typescript
Format.Set('palindrome', value => value === value.split('').reverse().join(''))
```

Once set, this format can then be used by the TypeCompiler and Value modules.

```typescript
const T = Type.String({ format: 'palindrome' })

const A = TypeCompiler.Compile(T).Check('engine')    // const A = false

const B = Value.Check(T, 'kayak')                    // const B = true
```


## Benchmark

This project maintains a set of benchmarks that measure Ajv, Value and TypeCompiler compilation and validation performance. These benchmarks can be run locally by cloning this repository and running `npm run benchmark`. The results below show for Ajv version 8.11.0. 

For additional comparative benchmarks, please refer to [typescript-runtime-type-benchmarks](https://moltar.github.io/typescript-runtime-type-benchmarks/).

### Compile

This benchmark measures compilation performance for varying types. You can review this benchmark [here](https://github.com/sinclairzx81/typebox/blob/master/benchmark/measurement/module/compile.ts).

```typescript
┌──────────────────┬────────────┬──────────────┬──────────────┬──────────────┐
│     (index)      │ Iterations │     Ajv      │ TypeCompiler │ Performance  │
├──────────────────┼────────────┼──────────────┼──────────────┼──────────────┤
│           Number │    2000    │ '    384 ms' │ '      9 ms' │ '   42.67 x' │
│           String │    2000    │ '    322 ms' │ '      8 ms' │ '   40.25 x' │
│          Boolean │    2000    │ '    310 ms' │ '      6 ms' │ '   51.67 x' │
│             Null │    2000    │ '    271 ms' │ '      6 ms' │ '   45.17 x' │
│            RegEx │    2000    │ '    491 ms' │ '     12 ms' │ '   40.92 x' │
│          ObjectA │    2000    │ '   2935 ms' │ '     44 ms' │ '   66.70 x' │
│          ObjectB │    2000    │ '   3076 ms' │ '     30 ms' │ '  102.53 x' │
│            Tuple │    2000    │ '   1274 ms' │ '     22 ms' │ '   57.91 x' │
│            Union │    2000    │ '   1281 ms' │ '     22 ms' │ '   58.23 x' │
│          Vector4 │    2000    │ '   1602 ms' │ '     17 ms' │ '   94.24 x' │
│          Matrix4 │    2000    │ '    959 ms' │ '     10 ms' │ '   95.90 x' │
│   Literal_String │    2000    │ '    337 ms' │ '      6 ms' │ '   56.17 x' │
│   Literal_Number │    2000    │ '    376 ms' │ '      5 ms' │ '   75.20 x' │
│  Literal_Boolean │    2000    │ '    370 ms' │ '      5 ms' │ '   74.00 x' │
│     Array_Number │    2000    │ '    733 ms' │ '      9 ms' │ '   81.44 x' │
│     Array_String │    2000    │ '    764 ms' │ '     10 ms' │ '   76.40 x' │
│    Array_Boolean │    2000    │ '    818 ms' │ '      6 ms' │ '  136.33 x' │
│    Array_ObjectA │    2000    │ '   3744 ms' │ '     35 ms' │ '  106.97 x' │
│    Array_ObjectB │    2000    │ '   3893 ms' │ '     34 ms' │ '  114.50 x' │
│      Array_Tuple │    2000    │ '   2229 ms' │ '     16 ms' │ '  139.31 x' │
│      Array_Union │    2000    │ '   1705 ms' │ '     18 ms' │ '   94.72 x' │
│    Array_Vector4 │    2000    │ '   2261 ms' │ '     17 ms' │ '  133.00 x' │
│    Array_Matrix4 │    2000    │ '   1574 ms' │ '     14 ms' │ '  112.43 x' │
└──────────────────┴────────────┴──────────────┴──────────────┴──────────────┘
```


### Validate

This benchmark measures validation performance for varying types. You can review this benchmark [here](https://github.com/sinclairzx81/typebox/blob/master/benchmark/measurement/module/check.ts).

```typescript
┌──────────────────┬────────────┬──────────────┬──────────────┬──────────────┬──────────────┐
│     (index)      │ Iterations │  ValueCheck  │     Ajv      │ TypeCompiler │ Performance  │
├──────────────────┼────────────┼──────────────┼──────────────┼──────────────┼──────────────┤
│           Number │  1000000   │ '     37 ms' │ '      5 ms' │ '      5 ms' │ '    1.00 x' │
│           String │  1000000   │ '     31 ms' │ '     24 ms' │ '     13 ms' │ '    1.85 x' │
│          Boolean │  1000000   │ '     25 ms' │ '     25 ms' │ '     11 ms' │ '    2.27 x' │
│             Null │  1000000   │ '     32 ms' │ '     26 ms' │ '     10 ms' │ '    2.60 x' │
│            RegEx │  1000000   │ '    170 ms' │ '     48 ms' │ '     35 ms' │ '    1.37 x' │
│          ObjectA │  1000000   │ '    564 ms' │ '     36 ms' │ '     23 ms' │ '    1.57 x' │
│          ObjectB │  1000000   │ '   1000 ms' │ '     56 ms' │ '     40 ms' │ '    1.40 x' │
│            Tuple │  1000000   │ '    125 ms' │ '     27 ms' │ '     13 ms' │ '    2.08 x' │
│            Union │  1000000   │ '    316 ms' │ '     27 ms' │ '     14 ms' │ '    1.93 x' │
│        Recursive │  1000000   │ '   3308 ms' │ '    415 ms' │ '    183 ms' │ '    2.27 x' │
│          Vector4 │  1000000   │ '    135 ms' │ '     27 ms' │ '     12 ms' │ '    2.25 x' │
│          Matrix4 │  1000000   │ '    658 ms' │ '     44 ms' │ '     30 ms' │ '    1.47 x' │
│   Literal_String │  1000000   │ '     48 ms' │ '     26 ms' │ '     10 ms' │ '    2.60 x' │
│   Literal_Number │  1000000   │ '     49 ms' │ '     31 ms' │ '      9 ms' │ '    3.44 x' │
│  Literal_Boolean │  1000000   │ '     47 ms' │ '     28 ms' │ '     10 ms' │ '    2.80 x' │
│     Array_Number │  1000000   │ '    418 ms' │ '     38 ms' │ '     17 ms' │ '    2.24 x' │
│     Array_String │  1000000   │ '    466 ms' │ '     35 ms' │ '     22 ms' │ '    1.59 x' │
│    Array_Boolean │  1000000   │ '    403 ms' │ '     41 ms' │ '     24 ms' │ '    1.71 x' │
│    Array_ObjectA │  1000000   │ '  13596 ms' │ '   2861 ms' │ '   1759 ms' │ '    1.63 x' │
│    Array_ObjectB │  1000000   │ '  15767 ms' │ '   2798 ms' │ '   1991 ms' │ '    1.41 x' │
│      Array_Tuple │  1000000   │ '   1666 ms' │ '    103 ms' │ '     73 ms' │ '    1.41 x' │
│      Array_Union │  1000000   │ '   4738 ms' │ '    229 ms' │ '     87 ms' │ '    2.63 x' │
│  Array_Recursive │  1000000   │ '  56371 ms' │ '   7315 ms' │ '   2813 ms' │ '    2.60 x' │
│    Array_Vector4 │  1000000   │ '   2180 ms' │ '    106 ms' │ '     53 ms' │ '    2.00 x' │
│    Array_Matrix4 │  1000000   │ '  11795 ms' │ '    384 ms' │ '    313 ms' │ '    1.23 x' │
└──────────────────┴────────────┴──────────────┴──────────────┴──────────────┴──────────────┘
```


### Compression

The following table lists esbuild compiled and minified sizes for each TypeBox module.

```typescript
┌──────────────────────┬────────────┬────────────┬─────────────┐
│       (index)        │  Compiled  │  Minified  │ Compression │
├──────────────────────┼────────────┼────────────┼─────────────┤
│ typebox/compiler     │ '   49 kb' │ '   24 kb' │  '2.00 x'   │
│ typebox/conditional  │ '   42 kb' │ '   17 kb' │  '2.46 x'   │
│ typebox/format       │ '    0 kb' │ '    0 kb' │  '2.66 x'   │
│ typebox/guard        │ '   21 kb' │ '   10 kb' │  '2.07 x'   │
│ typebox/value        │ '   72 kb' │ '   33 kb' │  '2.16 x'   │
│ typebox              │ '   11 kb' │ '    6 kb' │  '1.91 x'   │
└──────────────────────┴────────────┴────────────┴─────────────┘
```


## Contribute

TypeBox is open to community contribution. Please ensure you submit an open issue before submitting your pull request. The TypeBox project preferences open community discussion prior to accepting new features.
