index.js

var httpStatusCodes = require('http').STATUS_CODES;
var util            = require('util');
var camelCase       = require('lodash.camelcase');
var capitalize      = require('lodash.capitalize');

/**
 * @param {Number}        [statusCode=500]
 * @param {String|Object} [messageOrProperties]
 * @param {Object}        [properties]
 */
function HttpError(statusCode, messageOrProperties, properties) {
    Error.call(this);
    Error.captureStackTrace(this, this.constructor);

    statusCode = statusCode || 500;
    properties = properties || {};

    if (messageOrProperties instanceof Object) {
        properties = messageOrProperties;
    } else if (typeof messageOrProperties === 'string') {
        properties.message = messageOrProperties;
    }

    Object.assign(this, properties);

    this.name       = upperCamelCase(httpStatusCodes[statusCode]) || statusCode + ' Error';
    this.statusCode = statusCode;
    this.status     = statusCode;
    this.message    = this.message || httpStatusCodes[statusCode];

    Object.defineProperties(this, {
        statusCode: { enumerable: false },
        status:     { enumerable: false },
        name:       { enumerable: false }
    });
}

util.inherits(HttpError, Error);

Object.keys(httpStatusCodes).forEach(function(statusCode) {
    statusCode = Number(statusCode);

    if (statusCode >= 400) {
        var SpecificHttpError = function(messageOrProperties, properties) {
            HttpError.call(this, statusCode, messageOrProperties, properties);
        };

        var upperCamelCasedStatusMessage        = upperCamelCase(httpStatusCodes[statusCode]);
        HttpError[upperCamelCasedStatusMessage] = SpecificHttpError;

        HttpError[statusCode] = SpecificHttpError;

        util.inherits(SpecificHttpError, HttpError);
    }
});

function upperCamelCase(string) {
    return capitalize(camelCase(string));
}

module.exports = HttpError;