I do not understand why it is necessary to have the async keyword before the function keyword. For the same reason that we have the * symbol before generator functions: They mark the function as extraordinary. They are quite similar in that regard – they add a visual marker that the body of this function … Read more
You’re quite correct that changing target is the wrong approach and changing lib is the correct approach, however you have specified the wrong version of the language. According to MDN, Object.entries was officially added in the ES2017 specification. “lib”: [“es2017”] is therefore what you must specify instead*. If you wish to add only the declarations … Read more
Is this ‘a thing’? Yes. It comes up every now and then, e.g. here. They’re known as IIAFEs 🙂 If you want to put focus on the arrow, you could also call them IIAAFs. Are there pitfalls here I should be aware of? Whenever you call a promise-returning function and don’t return the result to … Read more
You can’t do this as you imagine, because you can’t use await if it is not directly inside an async function. The sensible thing to do here would be to make the function passed to map asynchronous. This means that map would return an array of promises. We can then use Promise.all to get the … Read more
Two issues jump out: Your getData never returns anything, so its promise (async functions always return a promise) will be fulfilled with undefined if it doesn’t reject The error message clearly shows you’re trying to directly render the promise getData returns, rather than waiting for it to settle and then rendering the fulfillment value Addressing … 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
await is not a no-op. If the awaited thing is not a promise, it is wrapped in a promise, that promise is awaited. Therefore await changes the execution order (but you should not rely on it nevertheless): console.log(1); (async function() { var x = await 5; // remove await to see 1,3,2 console.log(3); })(); console.log(2); … Read more
You can’t do this as you imagine, because you can’t use await if it is not directly inside an async function. The sensible thing to do here would be to make the function passed to map asynchronous. This means that map would return an array of promises. We can then use Promise.all to get the … Read more
async/await only works with promises, not with streams. There are ideas to make an extra stream-like data type that would get its own syntax, but those are highly experimental if at all and I won’t go into details. Anyway, your callback is only waiting for the end of the stream, which is a perfect fit … Read more
Yes, you can easily write such a wrapper for asynchronous functions as well – just use async/await: function wrapper(f) { return async function() { // ^^^^^ try { return await f.apply(this, arguments); // ^^^^^ } catch(e) { customErrorHandler(e) } } } Or you use promises directly, like in this example that is more tailored to … Read more