View Full Version : URGENT:eval() not working in Firefox

05-03-2007, 09:56 AM
hi all,
I'm having a strange problem with eval function in firefox. I've a javascript function where in i'm setting the display property to inline or none.
This works perfect in IE. but whe I opened my page in Firefox, its not working. I tried to put some alert() at various places in the function, and found that it stops at a line before eval() function.

I wanted to know is there any equivalent way for this function.Or I'll have to change it....I'm going nuts, to figure it out.Please help......


05-03-2007, 10:24 AM
The only time that eval() is ever necessary in JS is when parsing code from an external source, such as JSON. There is almost certainly a better way to do whatever it is you're attempting to do. We can't tell you what it is without seeing the code, though.

05-03-2007, 10:48 AM
Well I've few rows in my page, whose display property i'm setting through.
For example,I've row as...

<tr id="trColaspe1" style="display:inline;"><td>........</td></tr>
<tr id="trColaspe2" style="display:none;"><td>........</td></tr>

Now on click on an image, i'm calling a javascript function to change the style settings with eval(). Example.....


This is working perfectly fine in IE. but in firefox, the function stops at this point.

I hope, I was able to explain what you wanted to know.


05-03-2007, 10:52 AM
No, not really. You've got a lot of bad coding practices going on. Never access elements as global objects (this will actually throw a warning in Firefox, it's so outdated), and there's absolutely no reason to use eval() there. Also, table rows shouldn't have display: inline; (or at least, not if you want them to behave like table rows); they should have display: table-row; by default in CSS2-compliant browsers, although IE treats them as "inline with magic." The safest option is to set display to an empty string, which will revert the property to its default value:
document.getElementById("trColaspe1").style.display = "none";
document.getElementById("trColaspe2").style.display = "";

05-03-2007, 11:26 AM
Technically, you should use the table.rows[index].cells[index] method, and give the table an id.

05-03-2007, 11:29 AM
I don't know about "technically should..." it would be better in some cases, but using getElementById() to obtain the row directly can be fine, if not quite as neat.

05-03-2007, 01:45 PM
Hey thanks a lot Twey,
I did change that eval to getElementById(), and it works.And i'll do check out with that "inline", property.

Thanks again...

05-03-2007, 02:08 PM
Yes.. display="" instead of inline. works perfect.

Thanks a lot again....


05-03-2007, 07:05 PM

Now that this is solved, and I have no problem with the solution (for backward compatibility though, using the rows collection would be a better approach, as would object testing), I would like to point out that in IE:


should work just as well as:


And, just as poorly in other browsers.

05-03-2007, 07:56 PM
I believe that point has already been established, but document.getElementById() should be used in all cases.

05-04-2007, 03:48 AM
document.getElementById() should be used in all cases.

Huh? There is often no need to get an element by its id. When it can be conveniently done in another way, sometimes that is all that is required. Sometimes it can actually be a superior approach. This is especially true if your goal is to have a minimal amount of code serviceable for the maximum number of browsers.

Not all cases lend themselves to this kind of approach. Even in those that do, I will not argue against the fact that getElementById can almost always still be used and that if used properly, will be effective in virtually all modern browsers.

This is still a far cry from 'should be used in all cases'.