invariant


A custom Facebook's invariant library which is a way to provide descriptive errors in development but generic errors in production.
Here are the changes:

1. In ES6 environment, there is no need to use format which is "/%s/g" stated in source code. As I prefer to use Hello ${username} instead.
2. In some cases, I need to differentiate errors by creating different instance for logging purposes. e.g:
``javascript
class ReduxError extends Error {
...
}
`

Install

With npm do:

`sh
npm install typed-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.

$3

When used with browserify, it'll use browser.js (instead of invariant.js) and the envify transform will inline the value of process.env.NODE_ENV.

$3

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