StereoTyped

TypeScript 1:1 schema validation, inspired by ArkType.

The goal of this library is to provide a way to write TypeScript-like type definitions that can be used to validate data at runtime.

Usage

Using StereoTyped is very similar to how you would write TypeScript types. To define a type, you can use the type function, which takes an object with the type definition. This function returns a validation function that throws an error when the input data does not match the type definition. Here is an example:

import { type } from 'stereotyped';

const parseUser = type({
  name: 'string',
  age: 'number',
  isCool: 'boolean',
  isAwesome: '"yes" | "no"',
  friends: 'string[]',
  'hobbies?': '[string, string]',
  address: {
    street: 'string',
    city: 'string',
    zip: 'number',
  },
});

const user = parseUser({
  name: 'John Doe',
  age: 42,
  isCool: true,
  isAwesome: 'yes',
  friends: ['Alice', 'Bob'],
  hobbies: ['coding', 'reading'],
  address: {
    street: '123 Main St',
    city: 'Springfield',
    zip: 12345,
  },
});

At this point, the user variable is typed as the following:

type User = {
  name: string;
  age: number;
  isCool: boolean;
  isAwesome: 'yes' | 'no';
  friends: string[];
  hobbies?: [string, string] | undefined;
  address: {
    street: string;
    city: string;
    zip: number;
  };
};

You can infer the parsed type of a schema by using the Infer util type from StereoTyped:

import { type, type Infer } from 'stereotyped';

const schema = type({
  name: 'string',
  age: 'number',
});

type User = Infer<typeof schema>;
// ^? { name: string, age: number }

Supported Types

StereoTyped supports the following types & features:

• string
• number
• boolean
• null
• undefined
• object
• Arrays
• Tuples
• Unions
• Literal types (strings, numbers, booleans)
• Nested objects
• Optional properties
• Required properties