help.js

//
// My 'exceptions.js' file
//
var createError = require('create-error');

/**
 * InvalidSubjectType exception
 *
 * This exception should be thrown if the subject type
 * provided to the object constructor doesn't exist.
 */
exports.InvalidSubjectType = function(type) {
    return createError('InvalidSubjectType', {
        messages: [
            "The subject type provided doesn't exist:",
            type
        ]
    });
};








//
// My 'subject.js' file
//
var exceptions = require('./exceptions.js');

/**
 * A Permission Subject.
 *
 * @param id
 * @param type
 * @constructor
 */
function Subject (id, type) {
    if (typeof type !== "string") throw exceptions.InvalidSubjectType(type);

    this.id = id;
    this.type = type;

    /**
     * Get the subject identifier.
     *
     * @returns {*}
     */
    this.getId = function() {
        return this.id;
    }

    /**
     * Get the subject type.
     *
     * @returns {string|*}
     */
    this.getType = function() {
        return this.type;
    }

}

new Subject(1, 1);




// The issue that I'm getting:
//	http://puu.sh/iIMhr/b644ff3493.png