How to produce a time delay in JavaScript for a chat App?
Question
I'm currently a beginner at JavaScript and predominantly code in Java. My Question is is regarding invoking the document.write("string here") periodically (every 1/2 seconds) to append any new unprinted chat message to the client. I earlier tried using the following code :
<html>
<body onload="yantra();">
<script type="text/javascript">
x = 0;
function yantra(){
document.write("Hello<br>");
i = 1;
for(i = 0; i < 100; i++){
setTimeout("writeOneNum()", 1000);
}
}
function writeOneNum(){
x =x + 1;
document.write(x+"<br>");
}
function blank(){}
</script>
</body>
</html>
Instead of it printing 1 to 100 every 1000 millisecond as I expected it to print; in actuality, it printed 1 to 100 at one go (meaning without any delay).
1 answers
solution1
1 ACCPTED 2010-01-12 11:28:25
Well, you are setting all the timeouts at once, so of course it fires them all at once. Your code will work with small modification to the loop:
function yantra(){
document.write("Hello<br>");
i = 1;
for(i = 0; i < 100; i++){
setTimeout("writeOneNum()", 1000 * i);
}
}
By multiplying the time with i , the first is fired instantly, the second at 1000 * 1 = 1000 ms, the third at 1000 * 2 = 2000 ms etc.
In your case, it could be wiser to consider the setInterval function:
function yantra(){
document.write("Hello<br>");
setInterval("writeOneNum()", 1000);
}
That will fire the writeOneNum() every second infinitely. To stop the interval at some point, take a look at clearInterval on that same link above.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.