Catch a javascript error in an external script file
I have a bit of JavaScript (Jquery Tools' Overlay) which may throw an exception when dropped on a page that uses it incorrectly, and I'm trying to handle it gracefully.
I have a general window.onerror handler to rescue these errors and report them back to the server, however that's not getting triggered.
I also cannot wrap a try/catch around this code, as it's being included as a remote script in HTML.
Any ideas on how you can rescue errors that an external script throws?
UPDATE: Here's the example. I should correct myself, window.onerror does get triggered, however the script does not continue running (in the example, the alert never alerts).
<html>
<script type="text/javascript">
window.onerror = function(e){ console.log("caught error: "+e); return true;}
</script>
<body>
<!-- this is the line in the dom that causes the script to throw -->
<a rel="nofollow"></a>
<script type="text/javascript" src="http://www.google.com/jsapi"></script>
<script type="text/javascript">google.load("jquery", "1.4.1");</script>
<script src="http://cdn.jquerytools.org/1.2.5/tiny/jquery.tools.min.js"></script>
<script type="text/javascript">
//this code will throw an error in jquery tools
$("a[rel]").overlay();
alert("it's ok, I still ran.");
</script>
</body>
</html>
Solution 1:
Define the error handler before any other script is loaded/executed.
<script>window.onerror = function(e){}</script>
<script src="external.js"></script>
<script>
function ole(){alert("Hi!")}
ole();
</script>
When your script contains a syntax error, the error handler won't be called though (edit: in some older browsers):
<script>window.onerror=function(e){alert("?")}
<script>
!@ //The error won't be caught.
</script>