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[npm-url]:https://npmjs.org/package/err-code
[downloads-image]:http://img.shields.io/npm/dm/err-code.svg
[npm-image]:http://img.shields.io/npm/v/err-code.svg
[travis-url]:https://travis-ci.org/IndigoUnited/js-err-code
[travis-image]:http://img.shields.io/travis/IndigoUnited/js-err-code/master.svg
[david-dm-url]:https://david-dm.org/IndigoUnited/js-err-code
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Create new error instances with a code and additional properties.


## Installation

```console
$ npm install err-code
// or
$ bower install err-code
```

The browser file is named index.umd.js which supports CommonJS, AMD and globals (errCode).


## Why

I find myself doing this repeatedly:

```js
var err = new Error('My message');
err.code = 'SOMECODE';
err.detail = 'Additional information about the error';
throw err;
```


## Usage

Simple usage.

```js
var errcode = require('err-code');

// fill error with message + code
throw errcode(new Error('My message'), 'ESOMECODE');
// fill error with message + code + props
throw errcode(new Error('My message'), 'ESOMECODE', { detail: 'Additional information about the error' });
// fill error with message + props
throw errcode(new Error('My message'), { detail: 'Additional information about the error' });
```

## Pre-existing fields

If the passed `Error` already has a `.code` field, or fields specified in the third argument to `errcode` they will be overwritten, unless the fields are read only or otherwise throw during assignment in which case a new object will be created that shares a prototype chain with the original `Error`. The `.stack` and `.message` properties will be carried over from the original error and `.code` or any passed properties will be set on it.


## Tests

`$ npm test`


## License

Released under the [MIT License](http://www.opensource.org/licenses/mit-license.php).
