Schema-types NPM

schema-types

This library provides runtime and compile-type type schema definition and validation.

Features

Zero dependencies!
High level of developer ergonomics
Full modern TypeScript support
IntelliSense support

Installation

$ yarn add schema-types

Example

import * as T from 'schema-types'

// NOTE: documentation comments on the properties will appear in IntelliSense
const userType = T.object({
  /** The user's name */
  name: T.string(),

  /** The user's age */
  age: T.number(),

  /** Is the user account locked? */
  locked: T.optional(T.boolean()),
})

// Create a compile-time type alias for the schema type
type User = T.TypeOf<typeof userType>

// Use the compile-time type
export const user: User = {
  name: 'Alice',
  age: 32,
}

// Unknown data from user input, an API response, etc
const data: unknown = ...

// Return any validation issues
T.validate(userType, data) //=> [] (no issues)

T.validate(userType, {name: 'Alice', age: '32'}) //=> [{type: 'INVALID_TYPE', message: 'Invalid type, expected number, got string 32', path: '/age'}]

// Use a type-guard to refine the type
if (T.is(userType, data)) {
  // data is typed as `User`
}

// T.assert() throws an error if the data fails to validate
try {
  T.assert(userType, data)
  // data is typed as `User` (using TypeScript's `asserts` return type)
} catch (error) {
  console.log(error.issues) // logs the issues causing validation failure
}

// Generate TypeScript code for codegen
T.code(userType) //=> {"name": string; "age": number; "locked"?: (boolean | undefined)}

Type Compatibility

Types:

TypeScript	schema-types
`any`	`T.any()`
`Array`	`T.array()`
`bigint`	`T.bigint()`
`boolean`	`T.boolean()`
`Function`	`T.function()`
`null`	`T.null()`
`number`	`T.number()`
`object`	`T.object()`
`Record<string, T>`	`T.map()`
`string`	`T.string()`
`undefined`	`T.undefined()`
`unknown`	`T.unknown()`
`void`	`T.void()`
Literals	`T.literal()`
Literal Union	`T.literalUnion()`
Tuple	`T.tuple()`
Union	`T.union()`
Intersection	`T.intersection()`