error-system/README.md

Your custom errors in your JavaScript code

# error-system

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Your custom errors in your JavaScript code!

Inspired by [node-errno](http://github.com/rvagg/node-errno).

Based on errors in [bitcore](https://github.com/bitpay/bitcore).

## Example

### createError
```js
var errorSystem = require('error-system')
var RequestError = errorSystem.createError('RequestError', 'Code: {0} (url: {1})')
var request = require('request')

var url = 'https://github.com/notfound11'
request(url, function (error, response) {
  if (error === null && response.statusCode !== 200) {
    error = new RequestError(response.statusCode, url)
  }

  if (error !== null) {
    // ErrorRequestError: Code: 404 (url: https://github.com/notfound11)
    console.error(error.stack.split('\n')[0])
  }
})
```

### extend
```js
var errorSystem = require('error-system')
var RequestError = errorSystem.extend(Error, [{
  name: 'RequestError',
  message: 'Code: {0} (url: {1})',
  errors: [
    {
      name: 'NotFound',
      message: 'Code: 404 (url: {0})'
    }
  ]
}])
var request = require('request')

var url = 'https://github.com/notfound11'
request(url, function (error, response) {
  if (error === null && response.statusCode !== 200) {
    if (response.statusCode === 404) {
      error = new RequestError.NotFound(url)
    } else if (response.statusCode !== 200) {
      error = new RequestError(response.statusCode, url)
    }
  }

  if (error !== null) {
    // ErrorRequestErrorNotFound: Code: 404 (url: https://github.com/notfound11)
    console.error(error.stack.split('\n')[0])
  }
})
```

## License

Code released under [the MIT license](https://github.com/fanatid/error-system/blob/master/LICENSE).