# Alert(null)

**URL:** <https://www.ruby-forum.com/t/alert-null/108676>\
**Category:** Rails\
**Created:** [July 5, 2007, 11:02pm UTC](https://www.ruby-forum.com/t/alert-null/108676 "2007-07-05T23:02:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mravo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e495f1/32.png) [@mravo](https://www.ruby-forum.com/u/mravo)\
**Post date:** [July 5, 2007, 11:02pm UTC](https://www.ruby-forum.com/t/alert-null/108676/1 "2007-07-05T23:02:58Z")

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## Hello, sometimes I get this “message” or error:

## try { alert(null); } catch (e) { alert(‘RJS error:\n\n’ + e.toString()); alert(‘alert(null);’); throw e }.

What does this mean? My app works fine and variables are passed ok. This  
time it poped up when I was using form\_remote\_tag to submit some  
selection field values to controller action.

Thanks for your help!

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**Author:** ![mravo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e495f1/32.png) [@mravo](https://www.ruby-forum.com/u/mravo)\
**Post date:** [July 5, 2007, 11:10pm UTC](https://www.ruby-forum.com/t/alert-null/108676/2 "2007-07-05T23:10:27Z")

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you might be trying to call render :update do … and updating a dom  
element that doesn’t exist…

Mike

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**Author:** ![mravo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e495f1/32.png) [@mravo](https://www.ruby-forum.com/u/mravo)\
**Post date:** [July 5, 2007, 11:29pm UTC](https://www.ruby-forum.com/t/alert-null/108676/3 "2007-07-05T23:29:49Z")

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Yes, you’re right. I was trying to display a variable that was null. I  
inserted some if sentances and things got messed up in the controller.  
Anyways, thanks for your effort, I’ll remeber this for the future tasks.  
cheers!