defunctzombie / node-httperrors

Handy JavaScript Error classes representing the standard HTTP errors. Easily extensible and subclassable.

node-httperrors

Exposes HTTP 4xx and 5xx status codes as JavaScript Error objects.

Installation

Make sure you have node.js and npm installed, then run:

npm install httperrors

Usage

var httpErrors = require('httperrors');

// Instantiate by name (UpperCamelCase):
var err = new httpErrors.NotFound('The thing you were looking for was not found');

console.warn(err.toString()); // NotFound [404]: The thing you were looking for was not found

if (identityCrisis) {
    throw new httpErrors.ImATeapot('Dude...');
}

The error type is exposed as a true property on the instances, so your error handling code becomes quite readable (and you can avoid using instanceof):

if (err.NotFound) {
    // ...
} else if (err.BadGateway) {
    // ...
}

You can also create an error by status code (useful when proxying):

function fetchSomething(cb) {
    var request = require('request');
    request('http://example.com/thething', function (err, response) {
        if (err) {
            return cb(new (httpErrors[response.statusCode] || httpErrors.BadGateway)());
        }
        // ...
    });
}

Creating your own Error classes:

var httpErrors = require('httperrors');

var MyError = httpErrors.createError({
    type: 'MyError',
    // Used when no message is handed to the constructor:
    msg: 'A slightly longer description of the error'
});

Instances can carry extra data about the error:

try {
    throw new httpErrors.Forbidden({
        msg: "The message", // Not mandatory
        data: {disallowedIds: [1, 3, 4, 6]}
    });
} catch(e) {
    console.warn(e.data); // {disallowedIds: [1, 3, 4, 6]}
}

Inheriting from an existing Error class:

var httpErrors = require('httperrors');

var NotFoundUnderTheBedError = httpErrors.createError({
    type: 'NotFoundUnderTheBed',
    msg: 'I looked under the bed, but it was not found'
}, httpErrors.NotFound);

Instances of this error walk and quack like httpErrors.NotFound instances, of course:

var ohDear = new NotFoundUnderTheBedError('No monsters today');
console.warn(ohDear.NotFound); // true
console.warn(ohDear.NotFoundUnderTheBed); // true

License

3-clause BSD license -- see the LICENSE file for details.