I’m being told awaiting a promise chain will break things in my code. Not necessarily, your two code snippets do indeed work the same (as long as someFunction() really returns a promise). What does it matter which one is used. What dangers does the first snippet introduce that the second one doesn’t? It’s harder to … Read more
Sounds like you want to branch, not to break – you want to continue as usual to the done. A nice property of promises is that they don’t only chain, but also can be nested and unnested without restrictions. In your case, you can just put the part of the chain that you want to … Read more
Wrapping code in a promise (like you’ve done) does not make it non-blocking. The Promise executor function (the callback you pass to new Promise(fn) is called synchronously and will block which is why you see the delay in getting output. In fact, there is no way to create your own plain Javascript code (like what … Read more
I’m assuming you know how to make a native XHR request (you can brush up here and here) Since any browser that supports native promises will also support xhr.onload, we can skip all the onReadyStateChange tomfoolery. Let’s take a step back and start with a basic XHR request function using callbacks: function makeRequest (method, url, … Read more
The promise will always log pending as long as its results are not resolved yet. You must call .then on the promise to capture the results regardless of the promise state (resolved or still pending): let AuthUser = function(data) { return google.login(data.username, data.password).then(token => { return token } ) } let userToken = AuthUser(data) console.log(userToken) … Read more
TL;DR Don’t use the pattern in the question where you get the promises, and then separately wait on them; instead, use Promise.all (at least for now): const [value1, value2] = await Promise.all([getValue1Async(), getValue2Async()]); While your solution does run the two operations in parallel, it doesn’t handle rejection properly if both promises reject. Details: Your solution … Read more
It seems to be best practice not to place multiple lines of business logic in the try body Actually I’d say it is. You usually want to catch all exceptions from working with the value: try { const createdUser = await this.User.create(userInfo); console.log(createdUser) // business logic goes here } catch (error) { console.error(error) // from … Read more
Why does response.json return a promise? Because you receive the response as soon as all headers have arrived. Calling .json() gets you another promise for the body of the http response that is yet to be loaded. See also Why is the response object from JavaScript fetch API a promise?. Why do I get the … Read more
To me, this result doesn’t make sense. By attaching to this promise chain, each then is implying the intent that it will be dependant upon the successful resolution of d1 and a result being passed down the chain No. What you are describing is not a chain, but just attaching all the callbacks to d1. … Read more
The problem here is that you are trying to await an array of promises rather than a Promise. This doesn’t do what you expect. When the object passed to await is not a Promise, await simply returns the value as-is immediately instead of trying to resolve it. So since you passed await an array (of … Read more