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Improving FAQ re Robby

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Jay McCarthy 2010-09-13 10:24:58 -06:00
parent 07227ed8f7
commit ee5811b930
1 changed files with 30 additions and 6 deletions
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36
collects/web-server/scribblings/faq.scrbl
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@ -69,14 +69,38 @@ from the MIT Cookie Eaters.
Note: It may be considered a great feature that URLs can be shared this way, because delegation is Note: It may be considered a great feature that URLs can be shared this way, because delegation is
easily built into an application via URLs. easily built into an application via URLs.
@section{IE ignores my CSS or behaves strange in other ways} @section{My browser displays my page strangely: my CSS is ignored, sections are missing, etc.}
@(require (for-label xml)) @(require (for-label xml
web-server/http/response-structs))
In quirks mode, IE does not parse your page as XML, in particular it will not recognize many instances of @(define xexpr @tech[#:doc '(lib "xml/xml.scrbl")]{X-expression})
"empty tag shorthand", e.g. "<img src='...' />", whereas the @web-server uses @racketmodname[xml]
to format XML, which uses empty tag shorthand by default. You can change the default with the @racket[empty-tag-shorthand] Most @web-server developers use @|xexpr|s for representing the
parameter: @racket[(empty-tag-shorthand 'never)]. HTML of their page. However, @|xexpr|s only represent XML and HTML is not exactly
XML. This is a common source of problems.
For example, XML allows the "empty tag shorthand", e.g. @litchar{<img src='...' />},
on every tag, while HTML occasionally requires an end tag, e.g. @link["http://www.w3.org/TR/html401/interact/forms.html#h-17.7"]{TEXTAREA}.
Similarly, XML allows an end tag, e.g. @litchar{<img src='...'></img>}, on every tag, while
HTML occasionally forbides an end tag, e.g. @link["http://www.w3.org/TR/html401/struct/objects.html#h-13.2"]{IMG}.
(Of course, browsers do not necessarily implement their HTML parsing as specified and may be more or less lenient towards
XML-like HTML, so your test browser may not treat these forms as problematic.)
Since the @web-server uses @racketmodname[xml] to format @|xexpr|s, it inherits @racketmodname[xml]'s default rendering behavior
in general and its use of "empty tag shorthand" in particular. @racketmodname[xml]'s is to always use this short hand. You
can change it with the @racket[empty-tag-shorthand] parameter.
You can also change your @xexpr so that an end tag is forced. For example, @racket['(textarea [(name "text")])] renders as
@litchar{<textarea name="text" />}, while @racket['(textarea [(name "text")] "")] renders as
@litchar{<textarea name="text"></textarea>}, because of the string content in the @|xexpr|.
You may think the @web-server could do a better job advertising that the contents it serves is more like XML by default. Unfortunately,
browser support for such @link["http://www.w3.org/TR/xhtml-media-types/#media-types"]{advertisement} is @link["http://www.w3.org/MarkUp/2004/xhtml-faq#ie"]{lacking}.
You can use @racket[make-xexpr-response] to easily customize your application's MIME type and response headers.
Finally, you may find Web browser inspectors such as the Safari Inspector, Firebug, and the Google Chrome error console to be useful
tools in identifying offending tags.
@section{How do I use templates ``dynamically"?} @section{How do I use templates ``dynamically"?}