tea-error

Custom error constructor factory.

Installation

tea-error is available on npm.

$ npm install tea-error

Usage

error (name)

• @param {String} name
• @return {Function} custom error constructor

The primary export for this module is a factory that will return a constructor for a custom error of the type/name that is specified.

var error = require('tea-error')
var TestError = error('TestError')
var err = new TestError('My error message.')

throw err

An error created/thrown from the custom constructor observes all of the expected Javascript behaviors of Error.

instanceof

The constructed error is an instanceof an Error.

var err = new Error()
var myerr = new TestError()

err.should.be.instanceof(Error)
myerr.should.be.instanceof(Error)
myerr.should.be.isntanceof(TestError)

name

The name property is defined like other "native" errors.

var err = new ReferenceError()
var myerr = new TestError()

err.should.have.property('name', 'ReferenceError')
myerr.should.have.property('name', 'TestError')

message

The message property is defined like all error and specified as the first argument during construction.

var err = new Error('Javascript error occurred')
var myerr = new TestError('Test error occurred')

err.should.have.property('message', 'Javascript error occurred')
myerr.should.have.property('message', 'Test Error occurred')

stack

If the environment provides the ability to capture a stack trace, it will be provided as the stack property. Please view your environments documentation to see if this is supported.

var err = new Error()
var myerr = new TestError()

if (Error.captureStackTrace) {
  err.should.have.property('stack')
  myerr.should.have.property('stack')
}

Construction

• @param {String} message
• @param {Object} properties
• @param {Callee} start stack function for captureStackTrace

Once the new constructor for an error has been created it can be used to construct errors just as normal javascript errors.

var TestError = require('tea-errors')('TestError')
var err = new TestError('that did not work right')

throw err

There are a number of additional arguments that can be specified upon construction to provide further insight into the error created.

properties

The second argument during construction can be an object of properties that will be merged onto the newly created error.

var err = new TestError('expected field value', { fields: [ 'username' ] })

err.should.have.property('fields')
  .an('array')
  .that.deep.equals([ 'username' ])

Note that if the name, message, and stack properties are defined in this custom properties object, they will be ignored as those keys are reserved.

start stack function

The start stack function is used by Error.captureStackTrace to indicate where the environment should start the visible stack trace. Modifying this value might be useful in situations where the internals of the module issuing the error are irrelevant to what occured. The most obvious example is providing feedback for an api method.

// api.js
var ApiError = require('tea-error')('ApiError')

exports.use = function (fn) {
  if ('function' !== typeof fn) {
    throw new ApiError('API .use only accepts functions', null, arguments.callee);
  }

  // etc.
}

// user.js
var api = require('./api.js)
api.use('a string?')

In this scenario the first line of the error stack will reference user.js-Ln:2 as opposed to api.js-Ln:5. See the stack example for a demonstration.

.toJSON ()

• @param {Boolean} include stack
• @return {Object} JSON
• @alias serialize

Convert this error into a serialized JSON object.

var err = new TestError('some message', { hello: 'universe' })
var json = err.toJSON();

json.should.deep.equal({
  name: 'TestError',
  message: 'some message',
  hello: 'universe',
  stack: '...'
});

If this method is called as err.toJSON(false) the stack property will not be included.

License

(The MIT License)

Copyright (c) 2012 Jake Luer [email protected] (http://qualiancy.com)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.