如何制作非阻塞的javascript代码? [英] How to make non-blocking javascript code?

问题描述

如何进行简单的非阻塞 Javascript 函数调用?例如:

How can I make a simple, non-block Javascript function call? For example:

  //begin the program
  console.log('begin');
  nonBlockingIncrement(10000000);
  console.log('do more stuff'); 

  //define the slow function; this would normally be a server call
  function nonBlockingIncrement(n){
    var i=0;
    while(i<n){
      i++;
    }
    console.log('0 incremented to '+i);
  }

输出

"beginPage" 
"0 incremented to 10000000"
"do more stuff"

如何形成这个简单的循环来异步执行并通过回调函数输出结果?我们的想法是不要阻止做更多的事情":

How can I form this simple loop to execute asynchronously and output the results via a callback function? The idea is to not block "do more stuff":

"beginPage" 
"do more stuff"
"0 incremented to 10000000"

我已经尝试过关于回调和延续的教程，但它们似乎都依赖于外部库或函数.他们都没有在真空中回答这个问题:如何编写非阻塞的 Javascript 代码！?

I've tried following tutorials on callbacks and continuations, but they all seem to rely on external libraries or functions. None of them answer the question in a vacuum: how does one write Javascript code to be non-blocking!?

^{在提问之前，我已经非常努力地搜索了这个答案；请不要以为我没看.我发现的一切都是 Node.js 特有的([1], [2], [3]、[4]、[5]) 或否则特定于其他函数或库([6], [7], [8], [9], [10], [11])，特别是 JQuery 和 setTimeout().请帮助我使用 Javascript 编写非阻塞代码，而不是使用 Javascript 编写的工具，例如 JQuery 和 Node.请在将其标记为重复之前重读该问题.}

^{I have searched very hard for this answer before asking; please don't assume I didn't look. Everything I found is Node.js specific ([1], [2], [3], [4], [5]) or otherwise specific to other functions or libraries ([6], [7], [8], [9], [10], [11]), notably JQuery and setTimeout(). Please help me write non-blocking code using Javascript, not Javascript-written tools like JQuery and Node. Kindly reread the question before marking it as duplicate.}

推荐答案

带有回调的 SetTimeout 是要走的路.但是，请了解您的函数作用域与 C# 或其他多线程环境中的不同.

SetTimeout with callbacks is the way to go. Though, understand your function scopes are not the same as in C# or another multi-threaded environment.

Javascript 不会等待函数的回调完成.

Javascript does not wait for your function's callback to finish.

如果你说:

function doThisThing(theseArgs) {
    setTimeout(function (theseArgs) { doThatOtherThing(theseArgs); }, 1000);
    alert('hello world');
}

您的警报将在您传递的函数之前触发.

Your alert will fire before the function you passed will.

区别在于警报阻止了线程，但您的回调没有.

The difference being that alert blocked the thread, but your callback did not.

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