define-error

define-error

Define errors without frills, but with stack traces and instanceof support.

example

First, create and expose a singleton that defines your errors such as errors.js:

var defineError = require('define-error')

module.exports.DatabaseError = defineError('DatabaseError')

module.exports.HttpResponseError = defineError('HttpResponseError', function (message, code) {
    this.code = code
})

Then use them:

var assert            = require('assert'),
    DatabaseError     = require('./errors').DatabaseError,
    HttpResponseError = require('./errors').HttpResponseError

function query () {
    throw new DatabaseError('No database to query silly')
}

function request () {
    throw new HttpResponseError('Nobody out there', 404)
}

try {
    query()
}
catch (err) {
    assert(err instanceof DatabaseError)
    assert(err instanceof Error)
    console.error(err)
}

try {
    request()
}
catch (err) {
    assert(err instanceof HttpResponseError)
    assert(!(err instanceof DatabaseError))
    assert(err instanceof Error)
    assert(err.code)
    console.error(err)
}

api

var defineError = require('define-error')

var CustomError = defineError('CustomError' [, initFunc])

Create an error constructor, CustomError(message). Error will be in the prototype chain. If an initFunc function is provided, it will be called in the context of the error being created with all arguments that were passed to the error constructor. This will happen after the message and stack properties are set on the error object.

install

With npm do:

npm install --save define-error

testing

npm test

Or to run tests in phantom: npm run phantom

coverage

npm run view-cover

This will output a textual coverage report.

npm run open-cover

This will open an HTML coverage report in the default browser.