Given the following examples, why is outerScopeVar undefined in all cases?  var outerScopeVar;  var img = document.createElement('img'); img.onload = function() {     outerScopeVar = this.width; }; img.src = 'lolcat.png'; alert(oute...

I would like to upload a file asynchronously with jQuery. This is my HTML:  <span>File</span> <input type="file" id="file" name="file" size="10"/> <input id="uploadbutton" type="butto...

I have service which returns an observable which does an http request to my server and gets the data. I want to use this data but I always end up getting undefined. What's the problem?  Service:  @Injectable() export class EventService {    con...

I am currently reading Async Javascript by Trevor Burnham.  This has been a great book so far.  He talks about this snippet and console.log being 'async' in the Safari and Chrome console. Unfortunately I can't replicate this. Here is th...

This question already has an answer here:                           JavaScript closure inside loops – simple practical example                                      43 answers                                     I am running an event loop of th...

I have an AngularJS service that I want to initialize with some asynchronous data. Something like this:  myModule.service('MyService', function($http) {     var myData = null;      $http.get('data.json').success(function (data) {...

I have just found that in react this.setState() function in any component is asynchronous or is called after the completion of the function that it was called in.  Now I searched and found this blog (setState() State Mutation Operation May Be Synch...

According to the docs, "Without middleware, Redux store only supports synchronous data flow". I don't understand why this is the case. Why can't the container component call the async API, and then dispatch the actions?   For exampl...

I have code that looks something like this in javascript:  forloop {     //async call, returns an array to its callback }   After ALL of those async calls are done, I want to calculate the min over all of the arrays.  How can I wait for all of them...

I have a question regarding the native Array.forEach implementation of JavaScript: Does it behave asynchronously? For example, if I call:  [many many elements].forEach(function () {lots of work to do})   Will this be non-blocking?...