es6-promise

I'm trying to wrap my head around promises, and how JavaScript works with it's queue and event loop etc. I thought that if I put a slow synchronous function inside a promise, that slow sync function would be delegated to the background and I could use .then to deal with it when it was done. function syncSleep(ms){ var end = new Date().getTime() + ms; var start = new Date().getTime(); while (start < end) { start = new Date().getTime(); } } function p() { return new Promise(function(resolve) { syncSleep(5000); resolve("syncSleep done!"); }); } p().then( function(s) { var div = document

I need a simple debounce function with immediate always true. Without resorting to lodash and with the help of Can someone explain the "debounce" function in Javascript , I implemented it as following, function debounce(func, wait) { var timeout; return function() { if (!timeout) func.apply(this, arguments); clearTimeout(timeout); timeout = setTimeout(()=>{timeout = null}, wait); }; }; It works as expected until I need to debounce axios request. Assumed I have a debounced axios method, I would like the calling method to be as usual, which means my debounced axios method should return promise I

I have two promises, one rejected and other resolved. Promise.all is called. It executed the catch block of Promise.all as one of the promises is rejected. const promise1 = Promise.resolve('Promise 1 Resolved'); const promise2 = Promise.reject('Promise 2 Rejected'); const promise3 = Promise.all([promise1, promise2]) .then(data => { console.log('Promise.all Resolved', data); }) .catch(error => { console.log('Promise.all REJECTED', error); }) setTimeout(() => { console.log(promise1, promise2, promise3) }, 200); If I don't have the catch on Promise.all(), the value remains as Rejected, ie const

I created a NativeScript app with angular 2, i have an array of objects that i expect to see in the frontend of the application. the behaviour is that if i push an object into the array directly inside the ngOnInit() it works, but if i create a promise in the ngOnInit() it doesn't work. here is the code: export class DashboardComponent { stories: Story[] = []; pushArray() { let story:Story = new Story(1,1,"ASD", "pushed"); this.stories.push(story); } ngOnInit() { this.pushArray(); //this is shown var promise = new Promise((resolve)=>{ resolve(42); console.log("promise hit"); }); promise.then(x

I have a helper function for using fetch with CouchDB which ends as: ... return fetch(...) .then(resp => resp.ok ? resp.json() : Promise.reject(resp)) .then(json => json.error ? Promise.reject(json) : json) and when I use it elsewhere, I was under the impression that I could .catch those explicit rejections: above_function(its_options) .then(do_something) .catch(err => do_something_with_the_json_error_rejection_or_resp_not_ok_rejection_or_the_above(err)) but alas, I can't seem to be able to get a hold of the rejections. The specific error I'm after is a HTTP 401 response. What gives? (Please

This question already has an answer here: How do I access previous promise results in a .then() chain? 17 answers I have the following promise chain: return fetch(request) .then(checkStatus) .then(response => response.json()) .then(json => ({ response: json })) .catch(error => ({ error })) Where checkstatus() checks if the request was successful, and returns an error if it wasn't. This error will be caught and returned. But, the problem is that I want to add the both response.statusText and the results of response.json() to the error. The problem is that when I parse it I lose the original