@imhonglu/type-guard

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Introduction

• A library providing zero dependencies type guard utilities.
• Provides a chaining API inspired by Jest's matcher pattern.
• Built on Proxy to minimize overhead and ensure type safety.

Table of Contents

• Installation
• Usage
• API Reference

Installation

npm install @imhonglu/type-guard

Usage

Type guards created using the composeGuards function can be negated using the not key.

For detailed usage examples, please refer to the API Reference.

import { composeGuards } from '@imhonglu/type-guard';

// Composing type guards
const has = composeGuards({
	length: (value: unknown): value is object & { length: number } =>
		typeof value === "object" && value !== null && "length" in value,
});
// {
//   length: [Function];
//   not: {
//     length: [Function];
//   };
// }

let value: unknown[] | number | undefined;

if (has.length(value)) { ... } // value is unknown[]
if (has.not.length(value)) { ... } // value is number | undefined

API Reference

• composeGuards - compose type guards
• negateGuards - negate type guards
• negateGuard - negate single type guard