Proposed change to typeof

Brendan Eich brendan at
Wed Nov 5 19:12:25 PST 2008

On Nov 5, 2008, at 5:40 PM, David-Sarah Hopwood wrote:

> Brendan Eich wrote:
>> On Nov 5, 2008, at 1:42 PM, David-Sarah Hopwood wrote:
>>> Of course not. In this case we were talking about a case in which IE
>>> and Opera do not implement an extension, and follow the existing  
>>> standard
>>> more closely in their implementations of 'typeof'.
>> Yes, I know, but the particular case involving an extension in two
>> browsers out of four does not prove the lack of web-breaking.
> Why not? If a particular site already breaks on IE and Opera, why  
> should
> we be overly concerned if it also breaks on a future version of  
> Firefox?

We are going in circles. I pointed to user-agent forked JS web  
content, which could work in all four major browsers. There is a lot  
of user-agent forked web content, mostly to cope with DOM differences  
but also sometimes JS/JScript differences -- including unknown,  
unintended JS vs. JScript dependencies hiding as latent bugs in the  
DOM-forked alternatives.

"The web" is not a unitary function that breaks (or not) on a given  
pure-JS input, ignoring the browser's identity. The browser and the  
user-agent sniffing in the input matter.


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