Combine Proxy with new Error().stack for tracing changes.

trace_changes.js

const o = {};
const n = new Proxy(o, {
  set: (obj, prop, value) => {
    obj[prop + '_trace'] = new Error().stack;
    obj[prop] = value;
    return true;
  }
});
n.a = 10;
console.log(JSON.stringify(n.a_trace, null, 2));