Webmaster Forum / HTML, CSS, Scripts / JavaScript / March 2006

I'm a Perl programmer by background, and JavaScript is dim second or
third choice. I have an AJAX application, and at one point in the code,
I need to be sure that an object has been created before I attach an
interface element to it. I've googled this subject, and none of the
results seemed to fit, or I'm too dense to put them into practice.

How would I make the following code pause, and keep checking several
times before gracefully moving on?

var gLoad = new Object();

/* gLoad will contain x number of elements in the format gLoad[key] =
value;

function someFunction() {
  // various other statements to load and parse an Asynchronus request
....
 
   for ( var i in gLoad ) {
     var isLoaded = checkLoadedStatus(i);
     
     /* the part I need help with:
        if checkLoadedStatus returns false, block for 500 miliseconds
        and try again. Stop trying after x attemps .. */
       
     // some function call that only happens if isLoaded = true;
     createSomeInterFaceElements( i );
   }
   
   return;
}

function checkLoadedStatus( objid ) {
  if ( document.getElementById ) {
     if ( document.getElementById( objid ) ) {
       return true;
     }
     else return false;
  }
  else alert('unsuppported option'); // and hope for the best
}

In Perl I would do something like (untested) :

my $waitcount = 0;

my $isLoaded = checkLoadedStatus( 'xxx' );
if ( ! $isLoaded ) {
  while ( $waitcount < 3 ) {
     sleep(1);
     last if $isLoaded = checkLoadedStatus('xxx');
     $waitcount ++;
  }
 
  if ( $isLoaded ) {
     # isLoaded is true do something
  }
}  
else {
  # isLoaded is true do something
}

sub checkLoadedStatus {
 # some logic that returns 1 or 0
}

Any help is appreciated.