node.js 6+ function for erroring when accessing an undefined property on an object, useful for application constant includes and such

gistfile1.txt

constants.js:

function disallowUndefinedAccess(obj) {
    const handler = {
        get(target, property) {
            if (property in target) {
                return target[property];
            }
            throw new ReferenceError(`Access unknown ${property.toString()}`);
        },
    };
    return new Proxy(obj, handler);
}

... define a bunch of constants, such as error messages, urls, file paths, constant service responses, things like that

module.exports = disallowUndefinedAccess({
    ...all the things you would export
});

in another file:

const c = require('constants.js');

console.warn(c.SOMETHING_NOT_IN_LIST);

-> ReferenceError: Access unknown SOMETHING_NOT_IN_LIST

Very useful when you are refactoring a bunch of things. :-D

We also use a similar paradigm in front-end development, where 

import { ABC } from './constants.js';

console.warn(ABC);

throws an error if constants.js does not actually export an ABC.