@kohanajs/mod-live-home/install/public_source/js/ping-update.js

The Live Homepage allow admin to refresh visitor's home page.

window.onHeartBeatUpdates = window.onHeartBeatUpdates || [];

(fn => (document.readyState !== 'loading') ? fn() : document.addEventListener('DOMContentLoaded', fn))(async ()=>{
  //skip ping if query string contain no-redirect=1
  if(/no[-_]redirect/.test(location.href))return;

  /**
   *
   * @param fn function to loop
   * @param interval in ms
   * @param range in ms, total random range, for example +-2500 = 5000
   */
  const heartbeat = (fn, interval=3000, range= 3000) => {
    const timeout = interval + ((Math.random() * range) - range * .5);

    setTimeout(()=>{
      fn(timeout);
      heartbeat(fn, interval, range);
    }, timeout);
  }

  const heartbeatFunction = async () => {
    const indicator = document.getElementById('ping-indicator');

    try{
      const time = Date.now();
      const rnd = Math.floor(Math.random()*100000);
      const state = await (await fetch( `/media/ping/update.json?r=${time}${rnd}`)).json();

      indicator.setAttribute('data-state', (!state.error) ? 'success' : 'warning');
      if(state.error)return;//soft error, display warning

      const lastUpdate = state.meta.last_update;
      const lastLocalUpdate = parseInt(indicator.getAttribute('data-last-update'));

      if(lastLocalUpdate < lastUpdate){
        const callbacks = window.onHeartBeatUpdates;
        for(let i = 0; i < callbacks.length; i++){
          await callbacks[i](state.payload);
        }
      }

      indicator.setAttribute('data-last-update', lastUpdate);
    }catch (e){
      //network error
      indicator.setAttribute('data-state', 'error');
      console.log(e);
    }
  }

  heartbeat(heartbeatFunction, 2000, 2000);
  await heartbeatFunction(0);
});