es6-promise

Suppose I have the following Promise : function doSomethingAsynchronous() { return new Promise((resolve) => { const result = doSomeWork(); setTimeout(() => { resolve(result); }), 100); }); } At which point in time is doSomeWork() called? Is it immediately after or as the Promise is constructed? If not, is there something additional I need to do explicitly to make sure the body of the Promise is run? Immediately, yes, by specification. From the MDN : The executor function is executed immediately by the Promise implementation, passing resolve and reject functions (the executor is called before

I'm currently experimenting with promises and have a really basic question! Within a promise chain, would it be bad practice to call a synchronous function? For example: .then(function(results) { if(checkIfResultInMemory(results) === true){ return getTotalFromMemory() } return results; }) Or should my sync functions be refactored to return promises also? Within a promise chain, would it be bad practice to call a synchronous function? No, it is not a bad practice at all. It is one of many expected and useful practices. You are perfectly free to call either synchronous functions within the

I am running a forEach loop on an array and making two calls which return promises, and I want to populate an object say this.options , and then do other stuff with it. Right now I am running into the async issue if i use the following code sample and i get into the then function first. $.when.apply($, someArray.map(function(item) { return $.ajax({...}).then(function(data){...}); })).then(function() { // all ajax calls done now }); This is working code below, but it only works for the first element in the array, because I call the resulting function in the .then of the response. I want to do

What can ES6 Classes provide, as a pattern of organization, to asynchronous code. Below is an example with ES7 async/await, can an ES6-class have an asynchronous method, or constructor in ES7? Can I do: class Foo { async constructor() { let res = await getHTML(); this.res = res } } And, if not how should a constructor work that does this? class Foo { constructor() { getHTML().then( function (res) { this.res = res } } } If neither of these patterns work, can a constructor (and moreover classes) in an ES6 class support any form of asynchronicity that operates on the object's state? Or, are they

My question is about performance in my NodeJS app... If my program run 12 iteration of 1.250.000 each = 15.000.000 iterations all together - it takes dedicated servers at Amazon the following time to process: r3.large: 2 vCPU, 6.5 ECU, 15 GB memory --> 123 minutes 4.8xlarge: 36 vCPU, 132 ECU, 60 GB memory --> 102 minutes I have some code similair to the code below... start(); start(){ for(var i=0; i<12; i++){ function2(); // Iterates over a collection - which contains data split up in intervals - by date intervals. This function is actually also recursive - due to the fact - that is run

Say I have a promise called myProm , and say I have success and error handlers called onSuccess and onError . Whenever my promise takes longer than 10 seconds to complete, I want a function called timeoutHandler to be executed, but if that happens, neither onSuccess nor onError should be executed. (Similarly, if either onSuccess or onError runs, I don't want my timeoutHandler to be executed.) I've come up with the following snippet for this. new Promise((suc, err) => { let outOfTime = false; const timeoutId = window.setTimeout(() => { outOfTime = true; timeoutHandler(); }, 10000); myProm.then(