W3C home > Mailing lists > Public > public-webapi@w3.org > March 2006

Re: ACTION-70: Define the scope chain of onFoo events reference issue-1

From: Maciej Stachowiak <mjs@apple.com>
Date: Tue, 14 Mar 2006 14:09:33 -0800
Message-Id: <BE63118D-5086-4D3E-A3C0-5255796526B1@apple.com>
Cc: "\"Web APIs WG (public)\"" <public-webapi@w3.org>
To: Jim Ley <jim@jibbering.com>


On Mar 14, 2006, at 12:16 PM, Jim Ley wrote:

>
> "Maciej Stachowiak" <mjs@apple.com>
>>> Inconsistency is very annoying for the author.
>>
>> 1) Safari, Firefox, Opera and IE all have live event listener   
>> attributes.
>
> IE does not, it only has live properties ie onclick=function() {}  
> works but setAttribute("onclick","alert(1)");  does not result in  
> an alert if you click it.  (you can pass a function as the 2nd  
> parameter to setAttribute, but that would be non-conformant, and  
> doesn't work in any other UA)

The fact that IE's setAttribute is buggy doesn't mean the attribute  
isn't live. It is. And in fact, passing a function value will be  
reflected in the DOM attribute's text value when you serialize the  
element.

>
> There are further differences, in Opera 8.5/9 and Mozilla:
>
> alert(document.body.getAttribute('onclick'));
> document.body.onclick=function() { chicken() }
> alert(document.body.getAttribute('onclick'));
>
> the getAttribute doesn't reflect the change to the onclick property  
> - but does result in the function being called not the attribute,  
> so the UA's are not simply re-executing the attribute at each point  
> in time, so it's not clear why changing the attribute should have  
> an effect.

They don't "re-execute the attribute" but they do treat changes to  
the attribute as updating the event listener. The conceptual model  
doesn't involve executing the attribute at all, it is made into a  
function.

The DOM has other areas where there is both an element attribute and  
a corresponding DOM attribute, and both have an effect when changed  
but changing the DOM property doesn't necessarily affect the attribute.

In any case, this doesn't seem like a reason to reverse the behavior  
of setAttribute.

> In firefox 1.5:
>       document.body.onclick=function() { alert(2) }
>       document.body.setAttribute('onclick','alert(3)');
> results in both 2 and 3 being alerted.
>
> So I don't really agree that there is great consistency in  
> setAttribute and event properties, none of the 3 I've tested here  
> interopate at all - given that I would prefer to say only the one  
> that is universal - the property, is the one that should be used  
> and setAttribute should not, as that provides maximum compatibilty.

I agree that authors shouldn't set event listeners via setAttribute.  
But I don't think the spec should require setAttribute to have no  
effect on event listeners, since it does have an effect in current  
implementations.

Regards,
Maciej
Received on Tuesday, 14 March 2006 22:09:59 GMT

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