Create new error instances with a code and additional properties.

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

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

I find myself doing this repeatedly:

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

Simple usage.

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' });

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.

$ npm test

Released under the MIT License.