es6-promise

I have an async middleware in express, because I want to use await inside it, to clean up my code. const express = require('express'); const app = express(); app.use(async(req, res, next) => { await authenticate(req); next(); }); app.get('/route', async(req, res) => { const result = await request('http://example.com'); res.end(result); }); app.use((err, req, res, next) => { console.error(err); res .status(500) .end('error'); }) app.listen(8080); The problem is that when it rejects, it doesn't go to my error middleware, but if I remove the async keyword and throw inside a middleware it does.

ES6 Promises ES6 Promises are finite state machines and thus require complex implementations. Beyond that the Promise/A+ spec comes with a lot of rough edges: overloaded then (map/chain) recursive flattening / then-able assimilation automatic lifting several subscribers (multicast) eager evaluation Multicast distribution and eager evaluation are among other things the reasons why ES6 promises cannot be cancelled. Additionally, we can't add our own layers of then-ables with specific features, because they are immediately assimilated by recursive flattening. I am pretty sure there were a lot of

Say I have 4 functions: runA() , runB() , runC() and runD() . Using ES6 promises, in a completely successful run, these would all be run one after another: runA() .then(runB) .then(runC) .then(runD) If runA or runB fail (reject or throw), I would like to call error1() and then completely stop the chain (not call runC or runD ). This makes me think I should add a single .catch() at the very end of the .then promise chain: runA() .then(runB) .then(runC) //won't get called if runA or runB throws .then(runD) //won't get called if runA or runB throws .catch(error1) But if runC fails, I would like

I was trying to return result from FileReader and I found this implementation. But since it is outdated, I'm wondering how to implement the same using ES6 Promises or Rx Observables . Below is my code with reference to the aforementioned link and it works as expected. import { Injectable } from '@angular/core'; import * as XLSX from 'xlsx'; import * as XLS from 'xlsx'; @Injectable() export class ExcelReaderService { constructor() { } importFromExcel(ev): JQueryPromise<any> { let deferred = $.Deferred(); let regex = /^([a-zA-Z0-9\s_\\.\-:])+(.xlsx|.xls)$/; let workbook; let excelInJSON; if