I want to stop execution for 2 seconds.
<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>
For the first time loop is excute and sleep for 2 seconds. I want to stop execution for two seconds?
Before using this code, please read all comments.
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.
while command is being executed unlimited times by CPU, causing to freeze. See practical example - jsfiddle.net/mn6yagqx (test yourself)
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);
writeNext function output. If there are lines of code after writeNext(1); they will be executed right away.You can use setTimeout to do this
function myFunction() {
// your code to run after the timeout
}
// stop for sometime if needed
setTimeout(myFunction, 2000);
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().
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/
