method_missing.js

/* This can be the start of a module */

const makeHandler = cb => {
  return {
    get (object, prop, receiver) {
      if (Reflect.has(object, prop)) {
        return Reflect.get(...arguments)
      }

      return new Proxy(() => {}, {
        apply (method, thisArg, args) {
          cb.apply(object, [object, prop, ...args])
        }
      })
    }
  }
}

const withMethodMissing = (obj, cb) => {
  return new Proxy(obj, makeHandler(cb))
}

/* End of the 'withMethodMissing' module */

class FooBar {
}

const myFooBar = withMethodMissing(new FooBar(), (obj, method, ...args) => {
  console.log(`You have tried calling the missing method "${method}" with`, args)
})

myFooBar.iDoNotExist('bazinga', 42)