picostruct - a teeny tiny typescript validator

a really small (<1kB), extensible and simple to use typescript data validator

features

• Typescript first. Made with Typescript in mind. Better developer experience by introducing types to your unstructured data
• Small. No bloat, zero dependencies and tree-shakeable by design. Under 1 kB minified and brotlied. Uses this cool tool to control the size
• Simple to use. Just declare a schema that looks like your ordinary Typescript type and be done with it
• Easily extensible. Validators are just functions of type (x: any) => T that you can write yourself
• Transform values. In addition to simple validation, picostruct can transform and convert values into whatever you need
• Performant. Fast. Avoids memory allocations where possible
• Error reporting. A validation error contains information about where and why it occured, packaged into a simple ErrorInfo API

example

import { struct, array, map, filter, string, number, integer } from "picostruct"

const unixTimestamp = map(number(), x => new Date(x * 1000));
const cardNumber = filter(string(), x => true /* your validation logic here*/);
// validators and transformers are just functions
const custom = (x: any): number => +x;

const order = struct({
    cart: array([
        item: string(),
        qty: filter(integer(), x => x > 0),
    ]),

    payment: anyOf(
        {
            type: "paypal",
            email: string()
        },
        {
            type: "card",
            number: cardNumber(),
            cvc: filter(string(), x => x.length === 3),
            expiration: [integer(), integer()]
        }
    ),

    time: unixTimestamp(),
    custom: custom()
});

const request = order(JSON.parse("..."));
// now typescript knows about your type

alternatives

• superstruct - a more feature complete library with a similar API
• banditypes - even smaller validator library
• zod - probably the most popular typescript vaidation library