madeofsun / tiny-guards

A tiny library for advanced typescript guarding

tiny-guards 💂

A tiny library for advanced typescript guarding

• 🪶 lightweight

• 🍃 tree-shakable

• 🧱 composable

• 👮 type-safe

• 🔗 zero dependencies

• 🌚 dead simple

npm install tiny-guards

Usage example

import {
  gt,
  isNumber,
  isString,
  maxLen,
  oneOf,
  optional,
  refine,
  shape,
  Guard,
} from "tiny-guards";

const isNaturalNumber = refine(isNumber, Number.isSafeInteger, gt(0));
const isShortString = refine(isString, maxLen(16));
const isAccountType = oneOf(["reader", "publisher", "moderator"]);

const isUser = shape({
  id: isNaturalNumber,
  username: isShortString,
  accountType: isAccountType,
  firstName: optional(isString),
  lastName: optional(isString),
});

type User = Guard.Infer<typeof isUser>;

function doSomething(v: unknown) {
  if (isUser(v)) {
    v.id; // ✅
    v.username; // ✅
  }
}