How to handle external application unavialability

palchuri · Sep 18, 2007

<HTML>
<HEAD>
<TITLE>A document with SCRIPT</TITLE>
<META http-equiv="Content-Script-Type" content="text/tcl">
<SCRIPT type="text/javascript" src="

http://someplace.com/laucher.js">

</SCRIPT>
</HEAD>
<BODY>
<SCRIPT type="text/javascript">
if(isAppAvailable('code')){

// do something
}else{

// do something
}
</SCRIPT>
</BODY>
</HTML>

In this launcher.js is located on external application, which may not available some times. If the script is not available when I invoke isAppAvailable, getting JS error. Is there any way I can handle this situation so that user never see a JS error.

Thanks in advance.

Regards
Shri

BabyJeffy · Sep 18, 2007

Yes, you can test to see if a known function is present in the DOM.

Example launcher.js contains the following code:

Code:

function showVersion() {
  return "1.123v222";
}

You can then test (on the page) that this function is available using something like this:

Code:

function isAppAvailable() {
  return typeof showVersion === 'function';
}
if (isAppAvailable()) {
  // do something
} else {
  // handle the app not being available (yet)
}

Hope this makes some sense.

Cheers,
Jeff

[tt]Jeff's Blog [!]@[/!] CodeRambler

http://www.coderambler.com/

http://www.coedit.co.uk/

[/tt]

Make sure your web page and css validates properly against the doctype you have chosen - before you attempt to debug a problem!

FAQ216-6094

BillyRayPreachersSon · Sep 18, 2007

Put a try() catch() block around it. This assumes your users have a modern browser that supports this, of course (so not IE 5.5 or below).. For example:

Code:

try {
   if(isAppAvailable('code')) {
      ...
   }
}

catch(e) {
   alert('An error has occurred:\n\n' + e);
}

finally {
   // whatever here
}

Hope this helps,
Dan

Coedit Limited - Delivering standards compliant, accessible web solutions

[tt]Dan's Page [blue]@[/blue] Code Couch

http://www.codecouch.com/dan/

[/tt]

palchuri · Sep 18, 2007

Thanks guys for your help. I used try block because it is simple.

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How to handle external application unavialability

palchuri

Programmer

BabyJeffy

Programmer

BillyRayPreachersSon

Programmer

palchuri

Programmer

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