如何暂停 JavaScript 代码执行2秒

我想停止执行2秒钟。

<html>
<head>
<title> HW 10.12 </title>
<script type="text/javascript">
for (var i = 1; i <= 5; i++) {
document.write(i);
sleep(2); //for the first time loop is excute and sleep for 2 seconds
};
</script>
</head>
<body></body>
</html>

对于第一次循环是执行和休眠2秒钟。我想停止执行2秒钟？

423266 次浏览
小开

You can use setTimeout to do this

function myFunction() {
// your code to run after the timeout
}


// stop for sometime if needed
setTimeout(myFunction, 2000);
小开

There's no (safe) way to pause execution. You can, however, do something like this using setTimeout:

function writeNext(i)
{
document.write(i);


if(i == 5)
return;


setTimeout(function()
{
writeNext(i + 1);


}, 2000);
}


writeNext(1);
小开

This Link might be helpful for you.

Every time I've wanted a sleep in the middle of my function, I refactored to use a setTimeout().

小开

There's no way to stop execution of your code as you would do with a procedural language. You can instead make use of setTimeout and some trickery to get a parametrized timeout: 

for (var i = 1; i <= 5; i++) {
var tick = function(i) {
return function() {
console.log(i);
}
};
setTimeout(tick(i), 500 * i);
}

Demo here: http://jsfiddle.net/hW7Ch/

小开

Javascript is single-threaded, so by nature there should not be a sleep function because sleeping will block the thread. setTimeout is a way to get around this by posting an event to the queue to be executed later without blocking the thread. But if you want a true sleep function, you can write something like this:

function sleep(miliseconds) {
var currentTime = new Date().getTime();


while (currentTime + miliseconds >= new Date().getTime()) {
}
}

Note: The above code is NOT recommended.


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