bug#62429: 30.0.50; Add jsx faces to typescript-ts-mode

[Yuan Fu]

> On Mar 25, 2023, at 5:30 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> Cc: theo@thornhill.no
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Fri, 24 Mar 2023 16:49:35 -0700
>> 
>> Hey Theo, I want to add separate faces for JSX tags and attributes.
>> Otherwise users will be in a world of pain if they want to use different
>> fontification for JSX tag and funcall, and JSX attribute and constant. WDYT?
> 
> We never had any mode-specific faces for font-lock, AFAIK.  Why is
> this case different?  Why not use one of the existing font-lock faces,
> or even add new ones (but not specific to JSX)?
> 
> (Adding Stefan.)

IFIAK, css-mode has its own face. These two faces are specific to HTML and not 
widely applicable to other languages like other font-lock faces do.

JSX is basically HTML mixed with Javascript, so JSX tags and attributes are 
just HTML tags and attributes. Normally it’s fine to just use some semi-related 
font-lock face for them; mhtml.el uses function-call-face and constant-face for 
tags and attributes. But because in JSX, HTML tags and attribtues appear in the 
same buffer with Javascript code, if we use function-call-face and 
constant-face for tags and attributes, it’s impossible to change their 
appearance and not affect the functions and constants in Javascript code, 
because we are using the same face for JS functions and HTML tags, and JS 
constants and HTML attributes.

Yuan