Reactive state in vanilla JS

Simple test playing with Proxy and Reactive state in vanilla JS

Its just so simple

HTML

<section class="container" id="app">
    <h1>Type in input!</h1>
    <input type="text" onkeyup="state.tjo = this.value">
    <blockquote data-text="tjo"></blockquote>
</section>

JAVASCRIPT

const Observer = (target, listener) => {
      return new Proxy(target, {
        set: (obj, key, value) => {
          listener(obj);
      return Reflect.set(obj, key, value)
    },
    get: (obj, key) => {
          return Reflect.get(obj, key)
    }
  });
};

const state = Observer(
      {
        hello: "World",
    tjo: "test"
  },
  (state) => {
        Array.from(document.querySelectorAll("[data-text]")).map((el) => {
          el.innerText = state[el.dataset.text];
    });
  }
);

Live example at https://codepen.io/hugosp/pen/LYNrpWv?editors=1011