有没有比下面的pausecomp函数（取自此处）更好的方法来设计JavaScript中的睡眠？
function pausecomp(millis)
{
var date = new Date();
var curDate = null;
do { curDate = new Date(); }
while(curDate-date < millis);
}
这不是JavaScript中的Sleep的重复-动作之间的延迟；我希望在函数的中间有一个真正的睡眠，而不是在代码执行之前有一段延迟。
当前回答
现在还可以使用本机模块util来提供常规同步函数。
const { promisify } = require('util')
const sleep = promisify(setTimeout)
module.exports = () => {
await someAsyncFunction()
await sleep(2000)
console.log('2 seconds later...')
}
其他回答
JavaScript函数不允许任何暂停。使用同步JavaScript，可以实现过程。过程等待I/O操作和睡眠超时。它可用于JavaScript 1.7。
演示：
演示睡眠演示可暂停程序
首先，应该使用setTimeout和setInterval，因为JavaScript具有回调性质。如果您想使用sleep（），则是控制流或代码架构不正确。
尽管如此，我想我仍然可以帮助实现两个睡眠。
1.我头顶上的假同步跑步：
// A module to do that //dual-license: MIT or WTF [you can use it anyhow and leave my nickname in a comment if you want to]
var _ = (function(){
var queue = [];
var play = function(){
var go = queue.shift();
if(go) {
if(go.a) {
go.f();
play();
}
else
{
setTimeout(play, go.t);
}
}
}
return {
go:function(f){
queue.push({a:1, f:f});
},
sleep:function(t){
queue.push({a:0, t:t});
},
playback:play
}
})();
[也可以自动播放]
// Usage
_.go(function(){
// Your code
console.log('first');
});
_.sleep(5000);
_.go(function(){
// Your code
console.log('next');
});
// This triggers the simulation
_.playback();
2.实际同步运行
有一天，我对它进行了很多思考，我在JavaScript中真正睡觉的唯一想法就是技术。
睡眠函数必须是同步Ajax调用，超时设置为睡眠值。这就是真正睡觉的唯一方法。
我在JavaScript sleep/wait上搜索了很多网页。。。如果你想让JavaScript“RUN，DELAY，RUN”。。。大多数人得到的要么是“RUN，RUN（无用的东西），RUN”，要么是“RUN，RUN+延迟RUN”。。。
我想：这是一个有效的解决方案。。。但你必须把你的跑步代码切碎…：是的，我知道，这只是一个更容易理解的重构。。。还
示例1：
<html>
<body>
<div id="id1">DISPLAY</div>
<script>
// JavaScript sleep by "therealdealsince1982"; copyrighted 2009
// setInterval
var i = 0;
function run() {
// Pieces of codes to run
if (i == 0){document.getElementById("id1").innerHTML= "<p>code segment " + i + " is ran</p>"; }
if (i == 1){document.getElementById("id1").innerHTML= "<p>code segment " + i + " is ran</p>"; }
if (i == 2){document.getElementById("id1").innerHTML= "<p>code segment " + i + " is ran</p>"; }
if (i >2){document.getElementById("id1").innerHTML= "<p>code segment " + i + " is ran</p>"; }
if (i == 5){document.getElementById("id1").innerHTML= "<p>all code segment finished running</p>"; clearInterval(t); } // End interval, stops run
i++; // Segment of code finished running, next...
}
run();
t = setInterval("run()", 1000);
</script>
</body>
</html>
示例2：
<html>
<body>
<div id="id1">DISPLAY</div>
<script>
// JavaScript sleep by "therealdealsince1982"; copyrighted 2009
// setTimeout
var i = 0;
function run() {
// Pieces of codes to run, can use switch statement
if (i == 0){document.getElementById("id1").innerHTML= "<p>code segment " + i + " ran</p>"; sleep(1000);}
if (i == 1){document.getElementById("id1").innerHTML= "<p>code segment " + i + " ran</p>"; sleep(2000);}
if (i == 2){document.getElementById("id1").innerHTML= "<p>code segment " + i + " ran</p>"; sleep(3000);}
if (i == 3){document.getElementById("id1").innerHTML= "<p>code segment " + i + " ran</p>";} //stops automatically
i++;
}
function sleep(dur) {t=setTimeout("run()", dur);} // Starts flow control again after 'dur'
run(); // Starts
</script>
</body>
</html>
示例3：
<html>
<body>
<div id="id1">DISPLAY</div>
<script>
// JavaScript sleep by "therealdealsince1982"; copyrighted 2009
// setTimeout
var i = 0;
function flow() {
run(i);
i++; // Code segment finished running, increment i; can put elsewhere
sleep(1000);
if (i == 5) {clearTimeout(t);} // Stops flow, must be after sleep()
}
function run(segment) {
// Pieces of codes to run, can use switch statement
if (segment == 0){document.getElementById("id1").innerHTML= "<p>code segment " + segment + " is ran</p>"; }
if (segment == 1){document.getElementById("id1").innerHTML= "<p>code segment " + segment + " is ran</p>"; }
if (segment == 2){document.getElementById("id1").innerHTML= "<p>code segment " + segment + " is ran</p>"; }
if (segment >2){document.getElementById("id1").innerHTML= "<p>code segment "+ segment +" is ran</p>"; }
}
function sleep(dur) {t=setTimeout("flow()", dur);} // Starts flow control again after 'dur'
flow(); // Starts flow
</script>
</body>
</html>
示例4：
<html>
<body>
<div id="id1">DISPLAY</div>
<script>
// JavaScript sleep by "therealdealsince1982"; copyrighted 2009
// setTimeout, switch
var i = 0;
function flow() {
switch(i)
{
case 0:
run(i);
sleep(1000);
break;
case 1:
run(i);
sleep(2000);
break;
case 5:
run(i);
clearTimeout(t); // Stops flow
break;
default:
run(i);
sleep(3000);
break;
}
}
function run(segment) {
// Pieces of codes to run, can use switch statement
if (segment == 0){document.getElementById("id1").innerHTML= "<p>code segment " + segment + " is ran</p>"; }
if (segment == 1){document.getElementById("id1").innerHTML= "<p>code segment " + segment + " is ran</p>"; }
if (segment == 2){document.getElementById("id1").innerHTML= "<p>code segment " + segment + " is ran</p>"; }
if (segment >2){document.getElementById("id1").innerHTML= "<p>code segment " + segment + " is ran</p>"; }
i++; // Current segment of code finished running, next...
}
function sleep(dur) {t=setTimeout("flow()", dur);} // Starts flow control again after 'dur'
flow(); // Starts flow control for first time...
</script>
</body>
</html>
从该链接获取的代码不会冻结计算机。但它只在Firefox中有效。
/**
* Netscape compatible WaitForDelay function.
* You can use it as an alternative to Thread.Sleep() in any major programming language
* that support it while JavaScript it self doesn't have any built-in function to do such a thing.
* parameters:
* (Number) delay in millisecond
*/
function nsWaitForDelay(delay) {
/**
* Just uncomment this code if you're building an extension for Firefox.
* Since Firefox 3, we'll have to ask for user permission to execute XPCOM objects.
*/
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
// Get the current thread.
var thread = Components.classes["@mozilla.org/thread-manager;1"].getService(Components.interfaces.nsIThreadManager).currentThread;
// Create an inner property to be used later as a notifier.
this.delayed = true;
/* Call JavaScript setTimeout function
* to execute this.delayed = false
* after it finishes.
*/
setTimeout("this.delayed = false;", delay);
/**
* Keep looping until this.delayed = false
*/
while (this.delayed) {
/**
* This code will not freeze your browser as it's documented in here:
* https://developer.mozilla.org/en/Code_snippets/Threads#Waiting_for_a_background_task_to_complete
*/
thread.processNextEvent(true);
}
}
如果必须处理同步执行，我可以理解睡眠函数的用途。setInterval和setTimeout函数创建一个并行执行线程，该线程将执行序列返回到主程序，如果您必须等待给定的结果，这是无效的。当然，可以使用事件和处理程序，但在某些情况下，这不是预期的。
