const state = 0;

const view = state => {
  return `<div>
    <h1>${state}</h1>
    <button onclick='app.run("-1")'>-1</button>
    <button onclick='app.run("+1")'>+1</button>
  </div>`;
};

const update = {
  '+1': state => state + 1,
  '-1': state => state - 1
};

app.start('my-app', state, view, update);