[Ur] Thoughts on <meta> tags in Ur/Web?

foldr at tutanota.com foldr at tutanota.com
Fri Apr 15 20:24:05 EDT 2016


The most obvious choice is whitelisting, at least for for http-equiv, because 
the specification is relatively complex.
https://www.w3.org/TR/html401/struct/global.html#edef-META

Whitelisting for name attribute might be less usable, but I do not know 
whether it is important to add keywords for search engines these days. 
Probably not.
https://www.w3.org/TR/html401/appendix/notes.html#recs

Personally I am interested to see support for the use cases below.
    <meta charset="utf-8"/>
    <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>

At the moment I just define meta as
val meta : unit -> tag [Nam = string, Content = string, Http_equiv = string, 
Charset = string] head [] [] []


16. Apr 2016 10:35 by adamc at csail.mit.edu:


> Someone recently requested a nice way to include a <meta name="viewport" 
> content="..."> tag in Ur/Web.  It doesn't seem safe to expose <meta> in its 
> most general form, with type [string] for each attribute, since it seems 
> like browsers could interpret those strings in quite arbitrary ways, which 
> goes against Ur/Web's philosophy about implicit interpretation of strings 
> as programs.
>
> Are there any opinions, then, on the right way to expose this tag?
>
> My first thought is to add an application-level whitelist of which <meta> 
> names are allowed, just as with HTTP header names. Then the 'content' 
> attribute could be exposed as [string], while the 'name' attribute would 
> have an abstract type of allowable names. The programmer would need to be 
> careful not to whitelist names that can lead to mayhem.
>
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