throw-on

library0.8.0jsnpmunverified

A tiny zero-dependency TypeScript library (v0.8.0) that forces console.error/warn and network requests (fetch, XMLHttpRequest) to throw exceptions, failing tests or code paths early. Designed to catch React warnings like 'act(...)' or unmounted component updates, and unmocked network calls. Works in Node.js (>=14) and browsers. < 100 lines, fully tested, alternative to jest-fail-on-console with broader scope (not Jest-specific).

testing

npm install throw-on

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · THROW-ON

throw-on

testingjavascriptv0.8.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

throwOnConsole

✓ import { throwOnConsole } from 'throw-on'

✗ import throwOnConsole from 'throw-on'

Named export, not default.

throwOnFetch

✓ import { throwOnFetch } from 'throw-on'

✗ const throwOnFetch = require('throw-on').throwOnFetch

ESM-only; CommonJS require works but prefer named import.

restoreConsole

✓ import { restoreConsole } from 'throw-on'

✗ import { restoreConsole } from 'throw-on/restoreConsole'

All exports are from the main package entry, no subpath imports.

Shows how to enable throw-on for console.error, console.warn, and fetch in a test setup, including the ignore option.

import { throwOnConsole, throwOnFetch } from 'throw-on'; // In test setup (e.g., jest.setup.js) throwOnConsole('error'); throwOnConsole('warn'); throwOnFetch(); // Original console message still printed, then throws: // "throw-on console.error: ..." // Optional: ignore certain messages by substring or regex throwOnConsole('warn', { ignore: ['act('] });

Debug

Known issues

gotchaimport { throwOnConsole, throwOnFetch } from 'throw-on'

fix

Use named imports from the package, not from subpaths.

affects: >=0.0.0

gotchathrowOnConsole replaces the console method globally; calling restoreConsole is needed to revert.

fix

Always call restoreConsole in test teardown (e.g., afterEach) to avoid side effects.

affects: >=0.0.0

gotchathrowOnFetch does not ignore same-origin or data: URLs; all fetch calls throw.

fix

Manually mock fetch in tests instead of using throwOnFetch if you need selective behavior.

affects: >=0.0.0

deprecatedthrowOnXMLHttpRequestOpen is deprecated in favor of throwOnFetch for modern codebases.

fix

Use throwOnFetch instead, as XMLHttpRequest is legacy.

affects: <0.7.0

Errors

Common errors & fixes

Cannot find module 'throw-on' or its corresponding type declarations.

Missing installation or TypeScript not resolving package types.

fix

Run npm install --save-dev throw-on and ensure tsconfig.json includes node module resolution.

throw-on console.error: ...

throwOnConsole('error') is active and console.error was called.

fix

Either fix the code causing the console.error, or add the message to the ignore list.

TypeError: throwOnConsole is not a function

Default import instead of named import.

fix

Use import { throwOnConsole } from 'throw-on' (curly braces).

Upgrade

Version history

0.8.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

18 hits · last 30 days

node

Resources

githubhttps://github.com/tkrotoff/throw-on ↗

packagethrow-on ↗

homepagehttps://github.com/tkrotoff/throw-on#readme ↗