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diff --git a/app/static/doc/flask-docs/_sources/htmlfaq.txt b/app/static/doc/flask-docs/_sources/htmlfaq.txt deleted file mode 100644 index 1da25f3..0000000 --- a/app/static/doc/flask-docs/_sources/htmlfaq.txt +++ /dev/null @@ -1,207 +0,0 @@ -HTML/XHTML FAQ -============== - -The Flask documentation and example applications are using HTML5. You -may notice that in many situations, when end tags are optional they are -not used, so that the HTML is cleaner and faster to load. Because there -is much confusion about HTML and XHTML among developers, this document tries -to answer some of the major questions. - - -History of XHTML ----------------- - -For a while, it appeared that HTML was about to be replaced by XHTML. -However, barely any websites on the Internet are actual XHTML (which is -HTML processed using XML rules). There are a couple of major reasons -why this is the case. One of them is Internet Explorer's lack of proper -XHTML support. The XHTML spec states that XHTML must be served with the MIME -type `application/xhtml+xml`, but Internet Explorer refuses to read files -with that MIME type. -While it is relatively easy to configure Web servers to serve XHTML properly, -few people do. This is likely because properly using XHTML can be quite -painful. - -One of the most important causes of pain is XML's draconian (strict and -ruthless) error handling. When an XML parsing error is encountered, -the browser is supposed to show the user an ugly error message, instead -of attempting to recover from the error and display what it can. Most of -the (X)HTML generation on the web is based on non-XML template engines -(such as Jinja, the one used in Flask) which do not protect you from -accidentally creating invalid XHTML. There are XML based template engines, -such as Kid and the popular Genshi, but they often come with a larger -runtime overhead and, are not as straightforward to use because they have -to obey XML rules. - -The majority of users, however, assumed they were properly using XHTML. -They wrote an XHTML doctype at the top of the document and self-closed all -the necessary tags (``<br>`` becomes ``<br/>`` or ``<br></br>`` in XHTML). -However, even if the document properly validates as XHTML, what really -determines XHTML/HTML processing in browsers is the MIME type, which as -said before is often not set properly. So the valid XHTML was being treated -as invalid HTML. - -XHTML also changed the way JavaScript is used. To properly work with XHTML, -programmers have to use the namespaced DOM interface with the XHTML -namespace to query for HTML elements. - -History of HTML5 ----------------- - -Development of the HTML5 specification was started in 2004 under the name -"Web Applications 1.0" by the Web Hypertext Application Technology Working -Group, or WHATWG (which was formed by the major browser vendors Apple, -Mozilla, and Opera) with the goal of writing a new and improved HTML -specification, based on existing browser behaviour instead of unrealistic -and backwards-incompatible specifications. - -For example, in HTML4 ``<title/Hello/`` theoretically parses exactly the -same as ``<title>Hello</title>``. However, since people were using -XHTML-like tags along the lines of ``<link />``, browser vendors implemented -the XHTML syntax over the syntax defined by the specification. - -In 2007, the specification was adopted as the basis of a new HTML -specification under the umbrella of the W3C, known as HTML5. Currently, -it appears that XHTML is losing traction, as the XHTML 2 working group has -been disbanded and HTML5 is being implemented by all major browser vendors. - -HTML versus XHTML ------------------ - -The following table gives you a quick overview of features available in -HTML 4.01, XHTML 1.1 and HTML5. (XHTML 1.0 is not included, as it was -superseded by XHTML 1.1 and the barely-used XHTML5.) - -.. tabularcolumns:: |p{9cm}|p{2cm}|p{2cm}|p{2cm}| - -+-----------------------------------------+----------+----------+----------+ -| | HTML4.01 | XHTML1.1 | HTML5 | -+=========================================+==========+==========+==========+ -| ``<tag/value/`` == ``<tag>value</tag>`` | |Y| [1]_ | |N| | |N| | -+-----------------------------------------+----------+----------+----------+ -| ``<br/>`` supported | |N| | |Y| | |Y| [2]_ | -+-----------------------------------------+----------+----------+----------+ -| ``<script/>`` supported | |N| | |Y| | |N| | -+-----------------------------------------+----------+----------+----------+ -| should be served as `text/html` | |Y| | |N| [3]_ | |Y| | -+-----------------------------------------+----------+----------+----------+ -| should be served as | |N| | |Y| | |N| | -| `application/xhtml+xml` | | | | -+-----------------------------------------+----------+----------+----------+ -| strict error handling | |N| | |Y| | |N| | -+-----------------------------------------+----------+----------+----------+ -| inline SVG | |N| | |Y| | |Y| | -+-----------------------------------------+----------+----------+----------+ -| inline MathML | |N| | |Y| | |Y| | -+-----------------------------------------+----------+----------+----------+ -| ``<video>`` tag | |N| | |N| | |Y| | -+-----------------------------------------+----------+----------+----------+ -| ``<audio>`` tag | |N| | |N| | |Y| | -+-----------------------------------------+----------+----------+----------+ -| New semantic tags like ``<article>`` | |N| | |N| | |Y| | -+-----------------------------------------+----------+----------+----------+ - -.. [1] This is an obscure feature inherited from SGML. It is usually not - supported by browsers, for reasons detailed above. -.. [2] This is for compatibility with server code that generates XHTML for - tags such as ``<br>``. It should not be used in new code. -.. [3] XHTML 1.0 is the last XHTML standard that allows to be served - as `text/html` for backwards compatibility reasons. - -.. |Y| image:: _static/yes.png - :alt: Yes -.. |N| image:: _static/no.png - :alt: No - -What does "strict" mean? ------------------------- - -HTML5 has strictly defined parsing rules, but it also specifies exactly -how a browser should react to parsing errors - unlike XHTML, which simply -states parsing should abort. Some people are confused by apparently -invalid syntax that still generates the expected results (for example, -missing end tags or unquoted attribute values). - -Some of these work because of the lenient error handling most browsers use -when they encounter a markup error, others are actually specified. The -following constructs are optional in HTML5 by standard, but have to be -supported by browsers: - -- Wrapping the document in an ``<html>`` tag -- Wrapping header elements in ``<head>`` or the body elements in - ``<body>`` -- Closing the ``<p>``, ``<li>``, ``<dt>``, ``<dd>``, ``<tr>``, - ``<td>``, ``<th>``, ``<tbody>``, ``<thead>``, or ``<tfoot>`` tags. -- Quoting attributes, so long as they contain no whitespace or - special characters (like ``<``, ``>``, ``'``, or ``"``). -- Requiring boolean attributes to have a value. - -This means the following page in HTML5 is perfectly valid: - -.. sourcecode:: html - - <!doctype html> - <title>Hello HTML5</title> - <div class=header> - <h1>Hello HTML5</h1> - <p class=tagline>HTML5 is awesome - </div> - <ul class=nav> - <li><a href=/index>Index</a> - <li><a href=/downloads>Downloads</a> - <li><a href=/about>About</a> - </ul> - <div class=body> - <h2>HTML5 is probably the future</h2> - <p> - There might be some other things around but in terms of - browser vendor support, HTML5 is hard to beat. - <dl> - <dt>Key 1 - <dd>Value 1 - <dt>Key 2 - <dd>Value 2 - </dl> - </div> - - -New technologies in HTML5 -------------------------- - -HTML5 adds many new features that make Web applications easier to write -and to use. - -- The ``<audio>`` and ``<video>`` tags provide a way to embed audio and - video without complicated add-ons like QuickTime or Flash. -- Semantic elements like ``<article>``, ``<header>``, ``<nav>``, and - ``<time>`` that make content easier to understand. -- The ``<canvas>`` tag, which supports a powerful drawing API, reducing - the need for server-generated images to present data graphically. -- New form control types like ``<input type="date">`` that allow user - agents to make entering and validating values easier. -- Advanced JavaScript APIs like Web Storage, Web Workers, Web Sockets, - geolocation, and offline applications. - -Many other features have been added, as well. A good guide to new features -in HTML5 is Mark Pilgrim's soon-to-be-published book, `Dive Into HTML5`_. -Not all of them are supported in browsers yet, however, so use caution. - -.. _Dive Into HTML5: http://www.diveintohtml5.org/ - -What should be used? --------------------- - -Currently, the answer is HTML5. There are very few reasons to use XHTML -considering the latest developments in Web browsers. To summarize the -reasons given above: - -- Internet Explorer (which, sadly, currently leads in market share) - has poor support for XHTML. -- Many JavaScript libraries also do not support XHTML, due to the more - complicated namespacing API it requires. -- HTML5 adds several new features, including semantic tags and the - long-awaited ``<audio>`` and ``<video>`` tags. -- It has the support of most browser vendors behind it. -- It is much easier to write, and more compact. - -For most applications, it is undoubtedly better to use HTML5 than XHTML. |