express-response-errors/lib/http-error.js

Collection of custom response errors and middleware for express

'use strict'

const util = require('util')

const { STATUS_CODES } = require('http')

const ERROR_COLLECTION_BASE_VALUE = 400
const ERROR_COLLECTION_MAX_VALUE = 511

function HttpError (code, message = '') {
  if (
    typeof code !== 'number' ||
    code < ERROR_COLLECTION_BASE_VALUE || code > ERROR_COLLECTION_MAX_VALUE
  ) {
    throw new RangeError('Invalid HTTP status error code.')
  }

  this.code = code
  this.message = message || STATUS_CODES[code]
  if (Error.captureStackTrace) {
    Error.captureStackTrace(this, HttpError)
  }
}

util.inherits(HttpError, Error)

HttpError.prototype.name = 'HttpError'

function formatAsCamelCaseWord (word = '') {
  return word
    .replace(/\W+/g, '')
    .toLowerCase()
    .replace(
      /^\w/,
      char => char.toUpperCase()
    )
}

const appendErrIfNone = function (str = '') {
  return str
    .replace(/(error)+$/i, '')
    .concat('Error')
}

function errNameFromDesc (desc) {
  if (typeof desc !== 'string' || desc.length === 0) {
    return false
  }

  return appendErrIfNone(
    desc
      .split(/[\s-]/)
      .map(formatAsCamelCaseWord)
      .join('')
  )
}

function errorFactory (errors, code) {
  const parsedCode = parseInt(code, 10)

  if (parsedCode < ERROR_COLLECTION_BASE_VALUE) {
    return errors
  }

  let errorName = errNameFromDesc(STATUS_CODES[parsedCode])

  if (!errorName) {
    return errors
  }

  errors[errorName] = function (message = '') {
    errors[errorName].super_.apply(this, [parsedCode, message])
  }

  util.inherits(errors[errorName], HttpError)

  errors[errorName].prototype.name = errorName

  return errors
}

function getAllErrors () {
  return Object
    .keys(STATUS_CODES)
    .reduce(errorFactory, {})
}

const additionalHttpErrors = getAllErrors()

module.exports = {
  HttpError,
  ...additionalHttpErrors
}