buffer.js

function applyChanges() {
  this.isSaving = true;
  for (const key of Object.keys(this.buffer)) {
    this[key] = this.buffer[key];
  }
  this.buffer = {};
  delete this.isSaving;
}

function rollback() {
  this.buffer = {};
}

export const createProxy = (object) => {
  object.buffer = {};
  object.applyChanges = applyChanges.bind(object);
  object.rollback = rollback.bind(object);
  return new Proxy(object, {
    get(target, prop) {
      if (prop === 'isDirty') {
        return Boolean(Object.keys(target.buffer).length);
      }

      if (target.buffer[prop]) {
        return target.buffer[prop];
      }
      return target[prop];
    },
    set(obj, prop, value) {
      if (prop === 'isSaving') {
        obj[prop] = value;
      }

      if (prop === 'buffer') {
        obj[prop] = value;
      }

      if (!obj.isSaving) {
        obj.buffer[prop] = value;
      } else {
        obj[prop] = value;
      }
      return true;
    },
  });
};