Package Exports

err-object

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Readme

err-object

Custom error object.

Tired writing code like this:

const error = new SomeError('message')
error.code = 'SOME_ERROR'

There are tremendous modules about custom errors in the NPM, but NONE of those could be usable.

Install

$ npm install err-object

Usage

import err from 'err-object'
const message = 'message'

err(message)
// Error
// - message

err({
  message,
  name: 'ImplementError',
  code: 'ERR_IMPL'
})
// Error
// - message
// - name: 'ImplementError'
// - code: 'ERR_IMPL'

err(message, TypeError)
// TypeError
// - message

Creates error templates to manage multiple error types

import err, {Errors} from 'err-object'
import util from 'util'

const {
  E,
  error
} = new Errors()

// Error code, and message
E('ERR_NO_PERMISSION', 'you do not have permission to do this')

// Error code
E('ERR_INVALID_TYPE', {
  // Custom error type
  ctor: TypeError,
  // Message template which will be formatted by `util.format`
  message: 'number expected but got %s'
})

const factory = (code, preset, ...args) => {
  const {
    ctor = Error,
    message: messageTemplate,
    ...others
  } = preset

  const message = util.format(messageTemplate, ...args)
  return err({
    ...others,
    code,
    message
  }, Error)
}

E('ERR_INVALID_TYPE_2', {
  // Custom error type
  ctor: TypeError,
  // Message template which will be formatted by `util.format`
  message: 'number expected but got %s'

// We can define our custom error factory,
// and the default error factory is:
}, factory)

error('ERR_NO_PERMISSION')
// Error
// - code: 'ERR_NO_PERMISSION'
// - message: 'you do not have permission to do this'

error('ERR_INVALID_TYPE', 'string')
// TypeError
// - code: 'ERR_INVALID_TYPE'
// - message: 'number expected but got string'

error('ERR_INVALID_TYPE_2', 'string')
// The same return value of the last statement

// The constructor `Errors` accepts a `options.factory` parameter,
// to define the default error factory.
// And so the following statement is equivalent to `new Errors()`
new Errors({
  factory
})

err(thing, ctor)

thing String|Object
ctor Class=Error

new Errors(options)

options ?Object
- factory ?Function(code, preset, ...args) the default error factory (the default value please see above)
- notDefined ?Function(code, ...args) will create the error object if the given code is not defined.

error.E(code, preset, factory)

Define an error preset.

code string define the error code
preset ?Object
- ctor ?Error=Error the constructor of the error
- template ?string the message template which will be formatted by util.format()
- other property/properties that you want to add to the error object.
factory ?Function(code, preset, ...args) the error factory

Returns this

error.error(code, ...args)

code
args Array<any> which will be passed and spreaded into factory after the code and the preset parameters.

Returns Error And if a given code is not defined by error.E(), the return value will be notDefined(code, ...args)

License

MIT