Javascript object proxy

object_proxy.js

const original = {
    a: 1,
    b: {
        c: 1
    }
}

const handler = {
    get: (target, name) => {
        return target[name];
    },
    set: (obj, prop, value) => {
        const ori = obj[prop];
        obj[prop] = value;
        // listen to any update here.
        console.log(`mutation at ${prop}`);
        console.log(`>>> ${ori}`);
        console.log(`<<< ${value}`);
    }
}

const watched = new Proxy(original, handler);

watched.a = 2;

watched.b.c = 3;    // will not be watched.