Type Helpers Overview

npm install @zayne-labs/toolkit-type-helpers

import { isString, isNumber, isArray } from '@zayne-labs/toolkit-type-helpers';

const value: unknown = "hello";

if (isString(value)) {
  // TypeScript knows value is string here
  console.log(value.toUpperCase());
}

import type { Prettify, Writeable } from '@zayne-labs/toolkit-type-helpers';

type ReadonlyUser = {
  readonly id: string;
  readonly name: string;
};

// Remove readonly modifiers
type MutableUser = Writeable<ReadonlyUser>;
// Result: { id: string; name: string; }

import { assert, assertDefined } from '@zayne-labs/toolkit-type-helpers';

function processUser(user: User | null) {
  assertDefined(user);
  // TypeScript knows user is non-null here
  console.log(user.name);
}

import { defineEnum } from '@zayne-labs/toolkit-type-helpers';

const Status = defineEnum({
  PENDING: 'pending',
  ACTIVE: 'active',
  COMPLETED: 'completed'
} as const, { inferredUnionVariant: 'values' });

type StatusValue = typeof Status.$inferUnion;
// Result: 'pending' | 'active' | 'completed'