The Future of the Web » Hidden Ajax Errors with jQuery » HTML, CSS, JavaScript and Ajax Web Developer for Hire

Hidden Ajax Errors with jQuery
Jul 5 2007
If you use Ajax with jQuery, you may have noticed that you don't get any error messages when things go wrong. Even if you have major bugs in your callback functions, jQuery just silently fails, sweeping any errors under the rug, and leaving you clueless as to what just happened.

For example, you can do this and you won't get any errors:
```
$.get('page.html', function(){
    this_function_does_not_exist();
});
```
There are two ways to fix this. You can use $.ajax with the error parameter, passing an error handling function for that particular Ajax call. Or, you can define a global Ajax error handler. If you do a lot of Ajax, and you use Firebug, the latter is a great option. Try this:
```
$(document).ajaxError(function(){
    if (window.console && window.console.error) {
        console.error(arguments);
    }
});
```
After running this code, you'll start getting error messages in your Firebug console (if anything breaks with your Ajax calls or callbacks). The error messages aren't the greatest, but at least you don't have to stay in the dark any longer.

Tags: javascript jquery ajax
View 11 Comments | Add a comment
Comments

1. Jörn Zaefferer at 2:25pm on July 6, 2007

That's a great tip. That generic error handler inside jQuery's ajax method can be quite annoying otherwise. I wonder if these two lines should go into jQuery core...
2. Andy Cai at 7:25am on July 11, 2007

like the jquery.
3. jonnix at 9:15pm on November 8, 2007

Thank you very much. This tip helped me find an error I have been guessing for during 2 days.
4. Acronyms at 9:25am on April 2, 2008

I used similar way, put creating a separate function.
5. colin at 11:42pm on May 8, 2008

Thank you, this idea just saved me a lot of guess work
6. Braden at 1:55am on May 15, 2008

I'm confused--this doesn't seem to work with 1.2.3. Did they at one point try { success() } catch() { handleError(); }? I know Dojo does that, but I don't see it in 1.2.3 or 1.0.0.
7. Mat at 4:00pm on July 27, 2008

Thanks for the tip :)
8. Vlad at 6:25pm on September 2, 2008

Thank you!
9. LaPeGa at 8:51pm on November 26, 2008

Thanxxx
10. Ramiro at 10:06pm on March 6, 2009

Great Tip!!! specially the debug to console using firebug. Thanks
11. zoltantoth at 10:59pm on May 10, 2009

his is exactly what I was searching for. You could not explain it simplier.

Thank you.

P.s.:
I would draw your attention to the error in the comment engine:
If I use a single quote, you are double escape-ing it, so it throws an SQL error, so the shortened "could not" will not work.

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