Cache API Results

CacheAPIResults.js

const loadData = async (url) => {
  var data = localStorage.getItem(url);

  if (data) { // check if expired
    data = JSON.parse(data);
    if (Date.now() - data.timestamp > 600000) { // 10mins
      localStorage.removeItem(url);
      data = null;
    }
  }

  if (!data) { // load fresh
    data = await fetch(url).then(response => response.json());
    data.timestamp = Date.now();
    localStorage.setItem(url, JSON.stringify(data));
  }

  return data;
}