function promiseChain(chain, defaultValue = null) { let output = new Promise((resolve, reject) => { resolve(defaultValue); }); for (let i = 0; i < chain.length; i++) { let f = chain[i]; output = output.then(f); } return output; } function promiseWhile(callback) { let isDone = false; function done() { isDone = true; } let iterationDone = false; let p = callback(done).then(() => { iterationDone = true; }); let iid = setInterval(() => { if (iterationDone) { if (isDone) { clearInterval(iid); return; } iterationDone = false; callback(done).then(() => { iterationDone = true; }); } }, 100); } export { promiseChain, promiseWhile }