The following code segment demonstrates a recursive call using JavaScript.
function timedCount()
{
document.getElementById('txt').value=c;
c=c+1;
t=setTimeout("timedCount()",1000);
}
The source is from here.
My question: Doesn't this lead to a stack build-up and subsequently a stack overflow? I know for a fact that this will certainly crash in languages like Pascal and C/C++.
Thanks for any advice on this.
That's not real recursion and thus does not create a deep call stack.
However, you should never pass a string to setInterval() or setTimeout(). Doing so is as bad as using eval() and it results in potentially unreadable and possibly insecure code as soon as you use variables since you need to insert them into the string instead of passing the actual variable.
The proper solution is setTimeout(function() { /* your code *) }, msecs);. The same applies to setInterval(). If you just want to call a single function without any arguments, you can also pass the function name directly: setTimeout(someFunction, msecs); (note that there are no () behind the function name)
So in your case, use t = setTimeout(timedCount, 1000);
setInterval()?! That's a generic text for both cases and I even gave him an example using setTimeout. But I'll update it to make it clearear.
That isn't recursion, because your timedCount() function is not calling itself, it is calling setTimeout() to ask JS to call timeCount() asynchronously after the specified delay. The line after the one with setTimeout() - in this case just the end of the function - will execute immediately, it doesn't pause or sleep until after the timeout. So when you call timedCount() from somewhere else in your code timedCount() will finish executing and control will return to that other part of your code, then later the function will be called again via the timeout, which again causes another one to be scheduled for later execution (and so on ad infinitum). At no point is there a halfway finished timedCount() waiting for another one to finish executing like there would be with actual recursion.
If you did this:
function timedCount() {
// other code here
timedCount();
}
...then that would be recursion and would indeed crash since there are no conditions set to stop the recursion. If you add some control logic so that the recursion stops a "reasonable" number of levels deep that would be fine.
