Installation

Requirements

• Node.js 18+ / Bun 1+ / Deno 1.38+
• TypeScript 5.0+
• lodash (peer dependency — must be installed separately)

Package managers

npm

npm install assertcheck lodash
npm install -D @types/lodash   # optional, for IDE support

yarn

yarn add assertcheck lodash

pnpm

pnpm add assertcheck lodash

bun

bun add assertcheck lodash

JSR (Deno / Bun)

deno add jsr:assertcheck
bunx jsr add assertcheck

TypeScript config

assertcheck uses .ts extensions in imports and requires bundler module resolution. Make sure your tsconfig.json includes:

{
  "compilerOptions": {
    "module": "ESNext",
    "moduleResolution": "bundler"
  }
}

Verify the install

import { assert } from "assertcheck"

assert.equal(1, 1) // passes silently
assert.equal(1, 2) // throws AssertionError with formatted output