Sample code for demonstrating Proxy and Reflect usage.

proxyandreflect.js

function propDefaults(defaults) {
    const handler = {
        get (obj, prop) {
            return Reflect.get(obj, prop) || defaults[prop];
        }
    };
    return new Proxy({}, handler);
}

const palette = propDefaults({color: "yellow"});

console.log(palette.color) //yellow