An http error library
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An http error library

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Kapow! consolidates boilerplate HTTP information into a single easy-to-use library. You tell Kapow! that you want an error with a particular httpStatus code, and it fills in the basics for you. It defines and returns a RequestError object based on JavaScript's native Error object.


npm install kapow



To get an JavaScript Error object suitable for throwing or passing along, give Kapow! a status code, a message, and arbitrary data you want to include:

const Kapow = require('kapow');

var code = 404;
var message = 'Ain\'t nobody here here but us chickens.';
var data = {a: 1};
var err = Kapow(code, message, data);

// Returns:
//  { [RequestError: Ain't nobody here but us chickens.]
//    httpStatus: '404',
//    title: 'Not Found',
//    message: 'Ain\'t nobody here but us chickens.',
//    name: 'RequestError',
//    data: { a: 1 } }

All arguments to Kapow! are optional. Kapow! will try to figure out sensible defaults based on the information you did pass in.

This error can be either thrown immediately or passed on through your application to eventually send the user an informative HTTP response.

Wrapping an Existing Error:

If your app hands you an error, and you just want to decorate it, you can use the static wrap method on Kapow!:

const Kapow = require('kapow');

somePromise.then().catch(function(err) {
  Kapow.wrap(err, 404, 'Ain\'t nobody here at all.');

Changing Your Error:

Once you get the RequestError object back, you can augment it however you like:

const Kapow = require('kapow');

var err = Kapow(403, 'Don\'t you come back no more');

err.title = 'Hit the Road Jack';


// Returns:
//  { [RequestError: Don't you come back no more]
//    httpStatus: '403',
//    title: 'Hit the Road Jack',
//    message: 'Don\'t you come back no more',
//    name: 'RequestError',
//    data: undefined }

Don't Like Numbers?

You can call Kapow with the camelized version of the IETF's official error. See Kapow!'s complete error code list for all supported codes:

const Kapow = require('kapow');

var err = Kapow('forbidden', 'Fie! Forsooth Begone!');


// Returns:
//  { [RequestError: Fie! Forsooth Begone]
//    httpStatus: '403',
//    title: 'Forbidden',
//    message: 'Fie! Forsooth Begone',
//    name: 'RequestError',
//    data: undefined }