let fetchType; let fetchInterval; let fetchURL; onmessage = function(e) { let msgType = e.data.msgType; console.log("Configuration Message:"); console.log(e.data); fetchType = e.data.fetchType; fetchURL = e.data.fetchURL; fetchInterval = 1000 * e.data.fetchInterval; }; function doFetch() { let now = new Date(); if (fetchURL) { fetch(fetchURL).then( b => b.json()).then( j => postMessage({msgType: fetchType, json: j, timestamp: now})) .catch(e => console.log(e.message)); } } // Periodic resource fetching (function periodicFetch() { doFetch(); setTimeout(periodicFetch, fetchInterval); })();