---
title: assert
description: Use the Node.js assert module in Cloudflare Workers for testing assertions and value comparisons.
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# assert

Note

To enable built-in Node.js APIs and polyfills, add the nodejs\_compat compatibility flag to your [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/). This also enables nodejs\_compat\_v2 as long as your compatibility date is 2024-09-23 or later. [Learn more about the Node.js compatibility flag and v2](https://developers.cloudflare.com/workers/configuration/compatibility-flags/#nodejs-compatibility-flag).

The [node:assert ↗](https://nodejs.org/docs/latest/api/assert.html) module in Node.js provides a number of useful assertions that are useful when building tests.

JavaScript

```

import { strictEqual, deepStrictEqual, ok, doesNotReject } from "node:assert";


strictEqual(1, 1); // ok!

strictEqual(1, "1"); // fails! throws AssertionError


deepStrictEqual({ a: { b: 1 } }, { a: { b: 1 } }); // ok!

deepStrictEqual({ a: { b: 1 } }, { a: { b: 2 } }); // fails! throws AssertionError


ok(true); // ok!

ok(false); // fails! throws AssertionError


await doesNotReject(async () => {}); // ok!

await doesNotReject(async () => {

  throw new Error("boom");

}); // fails! throws AssertionError


```

Note

In the Workers implementation of `assert`, all assertions run in, what Node.js calls, the strict assertion mode. In strict assertion mode, non-strict methods behave like their corresponding strict methods. For example, `deepEqual()` will behave like `deepStrictEqual()`.

Refer to the [Node.js documentation for assert ↗](https://nodejs.org/dist/latest-v19.x/docs/api/assert.html) for more information.

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```