entangle-with-get-set.js

import { get, notifyPropertyChange } from '@ember/object';

export function inLocalStorage(
  target,
  propertyKey,
  descriptor
) {
  const targetName = target.constructor.name;
  const { initializer } = descriptor;

  return {
    configurable: true,
    enumerable: true,
    get() {
      const key = `${targetName}-${propertyKey}`;
      const lsValue = localStorage.getItem(key);
      const json = (lsValue && JSON.parse(lsValue)) || { value: initializer() };

      get(this, key);

      return json.value;
    },
    set(value) {
      const key = `${targetName}-${propertyKey}`;
      const lsValue = JSON.stringify({ value });

      localStorage.setItem(key, lsValue);

      // this is required to dirty the change tracking system
      notifyPropertyChange(this, keys);
    },
  };
}