JavaScript-同步等待异步操作(休眠) [英] JavaScript - sync wait for async operation (sleep)
问题描述
我知道它在这里被问过很多次，而且回答过很多次，这不是应该怎么做，而是再一次:)
I know it was asked here many times and many times answered this is not a way how it should be done, but once more again :)
是否可以通过某种方式调用异步功能(例如计时器/ajax调用)，基本上是常见的异步任务并同步等待直到其结束而没有100％CPU使用率和浏览器阻塞?
Is it possible, somehow, to call async function (such as timer / ajax call), basically common async task and synchronously wait until it ends without having 100%CPU usage and blocked browser?
简单的答案就足够了-是或否.如果没有，我必须以异步方式"根据异步操作编写所有代码，否则会更好;)
Simple answer is enough - yes or no. If no i have to write all code depending on the async operation in "async way" Otherwise, it would be better ;)
想象一下:
updateCSS("someurl.css")
function updateCSS(url) {
var css = getCachedResource(url);
css = css.replace(/regexp/gm, function(curUrl) {
base64 = atob(getCachedResource(curUrl))
return "data:image;base64," + base64
})
}
function getCachedResource(url) {
//...
if (cached) {
return cached
} else {
// doajax...
// watfor
return loaded
}
}
当然，我可以使它异步，但是代码将很糟糕.此外，我必须使调用此函数的所有函数异步.您能看到简单的解决方案吗?我会说封锁是最简单的.
Of course, I can make it async, but the code will be.... terrible. Moreover, I have to make async all functions calling this function. Can you see simple solution? Blocking would be simplest I would say.
谢谢
推荐答案
否，即使CPU使用率达到100％或浏览器被阻止，您也无法做到这一点.事情经过精心设计，可以防止您这样做.
No, you can't do that even with 100% cpu usage or a blocked browser. Things have been precisely engineered to prevent you from doing that.
这使得所有异步代码都是有毒的，这意味着所有调用异步函数(基于Promise或基于回调的代码)的代码本身都必须是异步的.
This makes all asynchronous code is poisonous, meaning all code that calls async functions (either promise or callback based) must be asynchronous itself.
关于可怕的代码:Promise链和async/await用于救援，它们可帮助您编写语法更好的异步代码. 不要害怕，请使用async/await，特别是如果您已经使用了Transpiler.
About the terrible code: Promise chains and async/await for the rescue, they help you to write asynchronous code with much better syntax. Don't be afraid, use async/await especially if you already use a transpiler.
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