async-await

问题 I am working with OpenWeatherMapAPI to calculate the sum of precipitation for the previous 5 days. To do this I have 5 async functions with api calls using the fetch api. The data received, that concerns me, is the hourly historic weather data spanning a 24 hour period. Full code bellow . The json response is stored to a constant (Ex. const histData1 ) where it is then iterated through to sum all of one values over that given 24 hour period. Note: humidity is used as a proof of concept

问题 I am working with OpenWeatherMapAPI to calculate the sum of precipitation for the previous 5 days. To do this I have 5 async functions with api calls using the fetch api. The data received, that concerns me, is the hourly historic weather data spanning a 24 hour period. Full code bellow . The json response is stored to a constant (Ex. const histData1 ) where it is then iterated through to sum all of one values over that given 24 hour period. Note: humidity is used as a proof of concept

问题 If I have the following code new Promise(res => res(1)) .then(val => console.log(val)) is this equivalent to let val = await new Promise(res => res(1)) console.log(val) I know one difference is that I have to wrap the second one in an async function, but otherwise are they equivalent? 回答1: Because your promise always resolves (never rejects), they are equivalent. You could also do: Promise.resolve(1).then(val => console.log(val)); Keep in mind that a major difference with await (besides it

问题 If I have the following code new Promise(res => res(1)) .then(val => console.log(val)) is this equivalent to let val = await new Promise(res => res(1)) console.log(val) I know one difference is that I have to wrap the second one in an async function, but otherwise are they equivalent? 回答1: Because your promise always resolves (never rejects), they are equivalent. You could also do: Promise.resolve(1).then(val => console.log(val)); Keep in mind that a major difference with await (besides it

问题 Look at this code: #![feature(async_closure)] use std::future::Future; use std::pin::Pin; trait A<'a> { fn call(&'a self, data: &'a i32) -> Pin<Box<dyn 'a + Future<Output=()>>>; } impl <'a, F, Fut> A<'a> for F where Fut: 'a + Future<Output=()>, F: Fn(&'a i32) -> Fut { fn call(&'a self, data: &'a i32) -> Pin<Box<dyn 'a + Future<Output=()>>> { Box::pin(self(data)) } } async fn sample(_data: &i32) { } fn is_a(_: impl for<'a> A<'a>) { } fn main() { is_a(sample); is_a(async move |data: &i32| {

问题 Look at this code: #![feature(async_closure)] use std::future::Future; use std::pin::Pin; trait A<'a> { fn call(&'a self, data: &'a i32) -> Pin<Box<dyn 'a + Future<Output=()>>>; } impl <'a, F, Fut> A<'a> for F where Fut: 'a + Future<Output=()>, F: Fn(&'a i32) -> Fut { fn call(&'a self, data: &'a i32) -> Pin<Box<dyn 'a + Future<Output=()>>> { Box::pin(self(data)) } } async fn sample(_data: &i32) { } fn is_a(_: impl for<'a> A<'a>) { } fn main() { is_a(sample); is_a(async move |data: &i32| {

问题 I have written a pretty simply script: { waiting: false, async handleWaiting(promise, timeout) { return new Promise((res, rej) => { let loadingStarted = false; const timeoutInstance = setTimeout(() => { loadingStarted = true; this.waiting = true; }, timeout); const onFinished = () => { if (loadingStarted) { this.waiting = false; } clearTimeout(timeoutInstance); } promise .then((result) => { onFinished(); res(result); }) .catch((ex) => { onFinished(); rej(ex); }); }); }, async searchForTerm

问题 I have a function which accepts a string and a path value and checks whether the path at the result returns a 1 or a -1. I fire the function with multiple requests and everything seems to be successful except for one. For example, if I call the function with 10 different URL's continously (one by one, not in an array), the promise is resolved for 9 but not for the 10th one. This is my code: enum Status { Queued = 0, Started = 1, Finished = 2, Failed = -1, } let dataFetchingTimer: number;

问题 I have a function which accepts a string and a path value and checks whether the path at the result returns a 1 or a -1. I fire the function with multiple requests and everything seems to be successful except for one. For example, if I call the function with 10 different URL's continously (one by one, not in an array), the promise is resolved for 9 but not for the 10th one. This is my code: enum Status { Queued = 0, Started = 1, Finished = 2, Failed = -1, } let dataFetchingTimer: number;

问题 why this code compiles var Person = function() { console.log("CALLED PERSON")}; Person.prototype.saySomething = function() { console.log("saySomething PERSON")}; var ape = new Person(); ape.saySomething(); and this code throws error Cannot set property 'saySomething' of undefined var Person = async function() { console.log("CALLED PERSON")}; Person.prototype.saySomething = function() { console.log("saySomething PERSON")}; var ape = new Person(); ape.saySomething(); 回答1: When you use async