As you already hinted in your question, your code creates all promises synchronously. Instead they should only be created at the time the preceding one resolves. Secondly, each promise that is created with new Promise needs to be resolved with a call to resolve (or reject). This should be done when the timer expires. That … Read more
No such synchronous inspection API exists for native JavaScript promises. It is impossible to do this with native promises. The specification does not specify such a method. Userland libraries can do this, and if you’re targeting a specific engine (like v8) and have access to platform code (that is, you can write code in core) … Read more
Is Promise.all(iterable) executing all promises? No, promises cannot “be executed”. They start their task when they are being created – they represent the results only – and you are executing everything in parallel even before passing them to Promise.all. Promise.all does only await multiple promises. It doesn’t care in what order they resolve, or whether … Read more
Shortly, the order is preserved. Following the spec you linked to, Promise.all(iterable) takes an iterable as a parameter and internally calls PerformPromiseAll(iterator, constructor, resultCapability) with it, where the latter loops over iterable using IteratorStep(iterator). Resolving is implemented via Promise.all() Resolve where each resolved promise has an internal [[Index]] slot, which marks the index of the … Read more
In case of CORS requests, browsers can only access the following response headers by default: Cache-Control Content-Language Content-Type Expires Last-Modified Pragma If you would like your client app to be able to access other headers, you need to set the Access-Control-Expose-Headers header on the server: Access-Control-Expose-Headers: Access-Token, Uid
The origin of this error lies in the fact that each and every promise is expected to handle promise rejection i.e. have a .catch(…) . you can avoid the same by adding .catch(…) to a promise in the code as given below. for example, the function PTest() will either resolve or reject a promise based … Read more
The return purpose is to terminate the execution of the function after the rejection, and prevent the execution of the code after it. function divide(numerator, denominator) { return new Promise((resolve, reject) => { if (denominator === 0) { reject(“Cannot divide by 0”); return; // The function execution ends here } resolve(numerator / denominator); }); } … Read more
Promise.all is all or nothing. It resolves once all promises in the array resolve, or reject as soon as one of them rejects. In other words, it either resolves with an array of all resolved values, or rejects with a single error. Some libraries have something called Promise.when, which I understand would instead wait for … Read more
Your best bet is to throw an Error wrapping the value, which results in a rejected promise with an Error wrapping the value: } catch (error) { throw new Error(400); } You can also just throw the value, but then there’s no stack trace information: } catch (error) { throw 400; } Alternately, return a … Read more
simple: var promiseResolve, promiseReject; var promise = new Promise(function(resolve, reject){ promiseResolve = resolve; promiseReject = reject; }); promiseResolve();