Javascript异步生成器 [英] Javascript Async Generator
本文介绍了Javascript异步生成器的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
是否可以编写如下的异步生成器:
Is it possible to write an asynchronous generator like the following:
function gen() {
return async function * () {
yield await ...
yield await ...
yield await ...
}()
}
所以可以像这样使用它,例如:
So one can use it like this, for example:
for (let val of await gen()) {
...
}
我无法弄清楚这种结构的语义,如何在循环中使用异步生成器?
I can't really work out the semantics of this construction, how are async generators used in loops?
推荐答案
在异步迭代提议完成之前,您可以从Redux-saga书中获取一个页面(如Cory Danielson所提到的),并有一个适配器函数可以执行所有异步/等待事务。
Until the async iteration proposal is complete, you could take a page from the Redux-saga book (like Cory Danielson mentioned) and have an adapter function that does all the async/await stuff.
const later = async (delay, value) => {
return new Promise(resolve => {
setTimeout(() => resolve(value), delay);
});
};
function* rangePromise() {
for (let i = 2; i < 10; i++) {
let nextValue = yield later(100, i);
yield nextValue;
}
}
const forEachAsyncAdapter = async (iterator, ...callbacks) => {
try {
let next = iterator.next();
while (!next.done) {
while (!next.done && next.value && next.value.then) {
next = iterator.next(await next.value);
}
if (!next.done) {
await callbacks.reduce(
async (nextValue, callback) => {
nextValue = await callback(await nextValue);
return nextValue;
},
Promise.resolve(next.value)
);
next = iterator.next();
}
}
} finally {
if (typeof iterator.return === 'function') {
iterator.return();
}
}
};
forEachAsyncAdapter(
rangePromise(),
async i => { console.log(i); return Array(i).join('a'); },
async s => { console.log(s); return s.toUpperCase(); },
async s => { console.log(s); }
);
这篇关于Javascript异步生成器的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文