I have a constructor function which registers an event handler:    function MyConstructor(data, transport) {     this.data = data;     transport.on('data', function () {         alert(this.data);     }); }  // Mock transport object var tran...

I've been developing JavaScript for a few years and I don't understand the fuss about promises at all.  It seems like all I do is change:  api(function(result){     api2(function(result2){         api3(function(result3){              // do...

I have a function callWithMagic which takes a callback function as a parameter and calls it with one argument.  const callWithMagic = callback => {   const magic = getMagic();   callback(magic); };   I also have a function processMagic which tak...

I want to know when an image has finished loading. Is there a way to do it with a callback?  If not, is there a way to do it at all?...

I have this counter I made but I want it to run forever, it's really simple, what am I doing wrong here?  function timer() {   console.log("timer!") }  window.setInterval(timer(), 1000)...

I'm trying to pass some parameter to a function used as callback, how can I do that?  function tryMe (param1, param2) {     alert (param1 + " and " + param2); }  function callbackTester (callback, param1, param2) {     callback (param1,...

As the title suggests. How do I do this?   I want to call whenAllDone() after the forEach-loop has gone through each element and done some asynchronous processing.  [1, 2, 3].forEach(   function(item, index, array, done) {      asyncFunction(item,...

I am getting the "object" value instead of the exact value. How do I get the value returned using a callback function?  function loadDB(option, callBack){     var dfd = new jQuery.Deferred(),         db = window.openDatabase('mydb',...

I'm currently writing JavaScript and confusing about callback. I've found it's not kind of built-in functions though... I'm now reading O'Relly JavaScript 5th Edition and it shows a sample code something like below:  getText = f...

Can someone give a clear definition together with a simple example that explains what is a "callback hell" for someone who does not know JavaScript and node.js ?  When (in what kind of settings) does the "callback hell problem" occu...