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Detect if an Applet is readyTag(s): Javascript interaction


<SCRIPT>
function isAppletReady(a) {
   return a.isActive();
   } 
</SCRIPT>

<FORM>
<INPUT TYPE=button 
   VALUE="Check applet" 
   onClick="if (!isAppletReady(document.applets[0])) alert("not ready");">
</FORM>
An Applet is ready when it's loaded and its init() method is done.

To execute a Javascript only when an Applet is ready :

<SCRIPT>
function waituntilok() {
   if (document.myApplet.isActive()) {
         doit();
         }
   else {
       settimeout(waituntilok(),5000)
       }
   }

function doit() {
    ....
    }
</SCRIPT>
...
<BODY onLoad="waituntilok();">

....

</BODY>
By calling the javascript function from the BODY onLoad handler, we can assume that the Applet is loaded, initiated and started.

Here a "browser friendly" solution from N. Witteman to check if an Applet can be loaded (or found).

<HTML>
<HEAD>
<SCRIPT LANGUAGE="JavaScript">

onError = errHandler;  
  // Without he parentheses, because we don't want IE
  // to do this. Like this, only NS does.

function appLoaded() {
 if (!document.applets[0].isActive)
    // in IE: isActive returns an error if the applet IS loaded, 
    // false if not loaded
    // in NS: isActive returns true if loaded, an error if not loaded, 
    // so never reaches the next statement
    alert("IE: Applet could not be loaded");
    }

function errHandler() {
 alert("NS: Applet could not be loaded");
 consume();
 // stops further processing of the error
 }

</SCRIPT>
</HEAD>

<BODY onLoad = appLoaded();>
<APPLET code=someClass.class
codeBase=someURL height=50 width=300><PARAM NAME="bgcolor" VALUE="FFFFFF">
</APPLET>
</BODY>
</HTML>

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