Runtime-overridable logger

example.ts

import {logger} from './lib/logger';

class X {
  get lgr() {
    return logger;
  }

  method() {
    this.lgr.info('called');
  }
}

const x = new X();

const y = new Proxy(x, {
  get(target, prop, receiver) {
    if (prop === 'lgr') {
      const lgr = logger.child({proxied: true});
      return lgr;
    }

    return target[prop];
  },
});

y.method();
// prints 
// {
//   "proxied": true,
//   "message": "called",
//   "level": "info",
//   "timestamp": "2019-05-24T00:43:36.881Z",
//   "ms": "+0ms"
// }