WebWorker Feature Check

feature.thread.js

self.onmessage = ({data}) => {
  self.postMessage(data.reduce((o, v, i) => {
    o[v] = !!self[v]
    return o;
  }, {}));
};

main.js

let checkWorkerFeatures = (features) => {
  return new Promise((resolve, reject) => {
    const threadCheck = new Worker('feature.thread.js');
    threadCheck.onmessage = ({data}) => resolve(data) && threadCheck.terminate();
    threadCheck.postMessage(features);
  })
};

checkWorkerFeatures(['WebSocket', 'localStorage', 'indexedDB']).then(console.log.bind(console));
// Logs: `Object {WebSocket: true, localStorage: false, indexedDB: true}` in latest Chrome:stable