# invariant

**Repository Path**: mirrors_fis-components/invariant

## Basic Information

- **Project Name**: invariant
- **Description**: Fork from https://github.com/zertosh/invariant.git
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-08-08
- **Last Updated**: 2026-07-18

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# invariant

[![Build Status](https://travis-ci.org/zertosh/invariant.svg?branch=master)](https://travis-ci.org/zertosh/invariant)

A mirror of Facebook's `invariant` (e.g. [React](https://github.com/facebook/react/blob/v0.13.3/src/vendor/core/invariant.js), [flux](https://github.com/facebook/flux/blob/2.0.2/src/invariant.js)).

## Install

With [npm](http://npmjs.org) do:

```sh
npm install invariant
```

## `invariant(condition, message)`

```js
var invariant = require('invariant');

invariant(someTruthyVal, 'This will not throw');
// No errors

invariant(someFalseyVal, 'This will throw an error with this message');
// Error: Invariant Violation: This will throw an error with this message
```

**Note:** When `process.env.NODE_ENV` is not `production`, the message is required. If omitted, `invariant` will throw regardless of the truthiness of the condition. When `process.env.NODE_ENV` is `production`, the message is optional – so they can be minified away.

### Browser

When used with [browserify](https://github.com/substack/node-browserify), it'll use `browser.js` (instead of `invariant.js`) and the [envify](https://github.com/hughsk/envify) transform will inline the value of `process.env.NODE_ENV`.

### Node

The node version is optimized around the performance implications of accessing `process.env`. The value of `process.env.NODE_ENV` is cached, and repeatedly used instead of reading `proces.env`. See [Server rendering is slower with npm react #812](https://github.com/facebook/react/issues/812)