Javascript: Is it ok to call cleartimeout before settimeout?

Question

I have a function that sets a timer, and calls itself back upon expiration of the timer.

What I'd like to know is if it is bad practice to clear the timer at the top of the function.

The reason for this is because I will be calling that function asynchronously from time to time, and if I don't clear the timer first, I'll have two running simultaneously.

I realize that I can clear the timer right before I make the other call to the function, but I'm wondering if it will cause problems in any browser if I just keep the cleartimeout call inside the function which contains the timer.

One other thought - Can I test the timer variable before making the cleartimeout call, to see if it is a timer?

Here is some example code:

function onAir(){      // reset timer       clearTimeout(timer);      $.getJSON("http://mywebsite.com?format=json&callback=?",function(data){         if(data.result == '1'){             do stuff here            }         else{             do other stuff here         }        });      // start timer     timer = setTimeout("onAir()",60000); }  

Thanks for sharing your brain with me!

Kenny

Answer 1

Yes, that's fine. Also, you should call "setTimeout()" like this:

  timer = setTimeout(onAir, 60000);