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Some work on script defer/async
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git-svn-id: http://svn.whatwg.org/webapps@49 340c8d12-0b0e-0410-8428-c7bf67bfef74
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Hixie committed May 3, 2006
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Expand Up @@ -35,7 +35,7 @@

<h1 id="web-applications">Web Applications 1.0</h1>

<h2 class="no-num no-toc" id="working">Working Draft &mdash; 1 May 2006</h2>
<h2 class="no-num no-toc" id="working">Working Draft &mdash; 3 May 2006</h2>

<p>You can take part in this work. <a
href="http://www.whatwg.org/mailing-list">Join the working group's
Expand Down Expand Up @@ -194,6 +194,10 @@

<li><a href="#the-elements"><span class="secno">2.2.8. </span>The
elements <span title="TBW">[TBW]</span></a>
<ul class="toc">
<li><a href="#elements"><span class="secno">2.2.8.1. </span>Elements
and documents</a>
</ul>
</ul>

<li><a href="#common0"><span class="secno">2.3. </span>Common
Expand Down Expand Up @@ -1542,7 +1546,7 @@ and suggestions on this to the list, btw).
<p id="html-namespace">To ease migration from HTML to XHTML, UAs conforming
to this specification will place elements in HTML in the
<code>http://www.w3.org/1999/xhtml</code> namespace, at least for the
purposes of the DOM and CSS. The term "<dfn id="elements">elements in the
purposes of the DOM and CSS. The term "<dfn id="elements0">elements in the
HTML namespace</dfn>", when used in this specification, thus refers to
both HTML and XHTML elements.

Expand Down Expand Up @@ -2010,9 +2014,6 @@ and suggestions on this to the list, btw).
<p>A call to <code>getElementsByClassName('aaa bbb')</code> would return
no nodes; none of the elements above are in the "aaa bbb" class.</p>
</div>

<p class="issue">We could also have a getElementBySelector() method, but it
seems that it would be best to let the CSSWG define that.</p>
<!-- XXX
> * xGetParentElementByClassName(rootElement, className, tagName) -
> Navigates upwards until we hit a parent element with the given class name and
Expand Down Expand Up @@ -2053,6 +2054,17 @@ and suggestions on this to the list, btw).
DOM APIs must always return tag names and attribute names in the original
case used to create those nodes.

<h5 id="elements"><span class="secno">2.2.8.1. </span>Elements and
documents</h5>

<p>An element is said to have been <dfn id="inserted" title="insert an
element into a document">inserted into a document</dfn> when either its
<code>parentNode</code> DOM attribute changes and its new value is the
<code>Document</code> in question, or, when the DOM node represented by
its <code>parentNode</code>, if any, has itself just been <span
title="insert an element into a document"><a href="#inserted">inserted
into a document</a></span>.

<h3 id="common0"><span class="secno">2.3. </span>Common microsyntaxes</h3>

<p>There are various places in HTML that accept particular data types, such
Expand Down Expand Up @@ -7326,8 +7338,8 @@ Address: &lt;input name="address"&gt;&lt;/p&gt;</pre>
attribute DOMString <code title="dom-script-text"><a href="#text">text</a></code>;
attribute DOMString <code title="dom-script-src"><a href="#src0">src</a></code>;
attribute DOMString <code title="dom-script-type"><a href="#type6">type</a></code>;
attribute boolean <code title="dom-script-defer">defer</code>;
attribute boolean <code title="dom-script-async">async</code>;
attribute boolean <code title="dom-script-defer"><a href="#defer">defer</a></code>;
attribute boolean <code title="dom-script-async"><a href="#async">async</a></code>;
};</pre>
</dl>

Expand All @@ -7336,76 +7348,128 @@ Address: &lt;input name="address"&gt;&lt;/p&gt;</pre>

<p>When the <dfn id="src" title="attr-script-src"><code>src</code></dfn>
attribute is set, the <code><a href="#script1">script</a></code> element
refers to an external file, which must (if it uses a supported scripting
language) be downloaded and executed. The user agent must delay the
execution of other scripts associated with the page that are invoked
during the download (e.g. event handlers) until after the external script
has been downloaded and executed.
refers to an external file. The value of the attribute must be a URI.

<p>If the <code title="attr-script-src"><a href="#src">src</a></code>
attribute is not set, then the script is given by the contents of the
element.

<p>The language of the script is given by the <dfn id="type5"
title="attr-script-type"><code>type</code></dfn> attribute. The value must
be a valid MIME type, optionally with parameters. <a
href="#refsRFC2046">[RFC2046]</a>

<p>For <code><a href="#script1">script</a></code> elements that have the
<code title="attr-script-src"><a href="#src">src</a></code> attribute set,
user agents may use the type given in this attribute to decide whether or
not to consider using the resource at all. If the UA does not support the
given MIME type as a scripting language, then the UA may opt not to
download the script.

<p>User agents must not consider the <code title="attr-script-type"><a
href="#type5">type</a></code> attribute authoritative, however &mdash;
upon fetching the script, user agents must only use the Content-Type
information associated with it to determine whether or not to execute it;
user agents must not use the <code title="attr-script-type"><a
href="#type5">type</a></code> attribute in the document to determine the
actual type of the script.

<p>If the <code title="attr-script-type"><a href="#type5">type</a></code>
attribute is omitted but the <code title="attr-script-src"><a
href="#src">src</a></code> attribute is set, then the UA must fetch the
resource to determine its type and thus determine if it supports (and can
execute) that external script.
<p><code><a href="#script1">script</a></code> elements have an associated
piece of metadata, a flag indicating whether or not the script block has
been <dfn id="already">"already executed"</dfn>. Initially, <code><a
href="#script1">script</a></code> elements must have this flag unset
(script blocks, when created, are not "already executed"). When a <code><a
href="#script1">script</a></code> element is cloned, the "already
executed" flag, if set, must be propagated to the clone when it is
created.

<p>If the <code title="attr-script-src"><a href="#src">src</a></code>
attribute is not set, then the script is given by the contents of the
element. The language is given by the <code title="attr-script-type"><a
href="#type5">type</a></code> attribute. If it is omitted, then the
default is the ECMAScript MIME type.</p>
<!--XXX <code>text/javascript</code>-->
<p><strong>When script blocks are run</strong>: When a <code><a
href="#script1">script</a></code> element whose "already executed" flag is
not set is <span>inserted into a document</span>, the user agent must act
as follows:

<p>When examining types to determine if they support the language, user
agents must not ignore unknown MIME parameters &mdash; types with unknown
parameters must be assumed to be unsupported.
<ol>
<li>
<p>First, if the element has a <code title="attr-script-src"><a
href="#src">src</a></code> attribute, then a load for the specified
content must be started.</p>

<li>
<p>Then, if the document is still being parsed, and the element has a
<code title="attr-script-defer">defer</code> attribute, then the element
must be added to the end of the <span>list of scripts that will execute
when the document has finished parsing</span>.</p>

<p>Otherwise, if the document is still being parsed, and the element has
a <code title="attr-script-async">async</code> attribute and a <code
title="attr-script-src"><a href="#src">src</a></code> attribute, then
the element must be added to the end of the <span>list of scripts that
will execute asynchronously</span>.</p>

<p>Otherwise, if the document is still being parsed, the element must be
<span title="executing a script block">executed</span> synchronously.</p>

<p>Otherwise, the document has finished being parsed; if the element has
no <code title="attr-script-src"><a href="#src">src</a></code>
attribute, the element must be <span title="executing a script
block">executed</span> synchronously.</p>

<p>Otherwise, the document has finished being parsed and the element has
a <code title="attr-script-src"><a href="#src">src</a></code> attribute:
the element must be added to the end of the <span>list of scripts that
will execute asynchronously</span>.</p>
</ol>

<p><strong>How to execute a script block:</strong> ...

<p class="big-issue">WIP</p>
<!--XXXXXXXXXXXXXXXXXXXX

<p>User agents that support scripting must execute scripts (written
in languages that they support) immediately upon parsing a
<code>script</code> element's end tag, and immediately upon having a
dynamically created <code>script</code> element inserted into the
DOM. Once a <code>script</code> element has been executed, it must
be flagged as such and never re-executed again. When an element with
this flag set is cloned, the new element must not have the flag
set.</p>

<p>For scripting languages that consist of pure text, user agents
must use the value of the DOM <code
title="dom-script-text">text</code> attribute (defined below) as the
script to execute. For XML-based scripting languages, user agents
must use all the children nodes of the <code>script</code>
element as the script.</p>

<p>User agents that support scripting must execute scripts (written in
languages that they support) immediately upon parsing a <code><a
href="#script1">script</a></code> element's end tag, and immediately upon
having a dynamically created <code><a href="#script1">script</a></code>
element inserted into the DOM. Once a <code><a
href="#script1">script</a></code> element has been executed, it must be
flagged as such and never re-executed again. When an element with this
flag set is cloned, the new element must not have the flag set.

<p>For scripting languages that consist of pure text, user agents must use
the value of the DOM <code title="dom-script-text"><a
href="#text">text</a></code> attribute (defined below) as the script to
execute. For XML-based scripting languages, user agents must use all the
children nodes of the <code><a href="#script1">script</a></code> element
as the script.</p>
<!-- XXXXXXXXXXXX -->
<!--
http://www.websiteoptimization.com/speed/tweak/defer/test/

internal deferred scripts execute before any external scripts execute, or before the LOAD if there are none
external deferred scripts execute before the LOAD

, which must (if it uses a supported scripting
language) be downloaded and executed. The user agent must delay the
execution of other scripts associated with the page that are invoked
during the download (e.g. event handlers) until after the external
script has been downloaded and executed

<p>For <code>script</code> elements that have the <code
title="attr-script-src">src</code> attribute set, user
agents may use the type given in this attribute to decide whether or
not to consider using the resource at all. If the UA does not
support the given MIME type as a scripting language, then the UA may
opt not to download the script.</p>

<p>User agents must not consider the <code
title="attr-script-type">type</code> attribute authoritative,
however &mdash; upon fetching the script, user agents must only use
the Content-Type information associated with it to determine whether
or not to execute it; user agents must not use the <code
title="attr-script-type">type</code> attribute in the document to
determine the actual type of the script.</p>

<p>If the <code title="attr-script-type">type</code> attribute is
omitted but the <code title="attr-script-src">src</code> attribute
is set, then the UA must fetch the resource to determine its type
and thus determine if it supports (and can execute) that external
script.</p>

<p>When examining types to determine if they support the language,
user agents must not ignore unknown MIME parameters &mdash; types
with unknown parameters must be assumed to be unsupported.</p>


-->

<p>The DOM attributes <dfn id="src0"
title="dom-script-src"><code>src</code></dfn> and <dfn id="type6"
title="dom-script-type"><code>type</code></dfn> each <span><a
title="dom-script-src"><code>src</code></dfn>, <dfn id="type6"
title="dom-script-type"><code>type</code></dfn>, <dfn id="defer"
title="dom-script-defer"><code>defer</code></dfn>, <dfn id="async"
title="dom-script-async"><code>async</code></dfn>, each <span><a
href="#reflect">reflect</a></span> the respective content attributes of
the same name.

Expand Down Expand Up @@ -19883,9 +19947,11 @@ function receiver(e) {

<p>If the next token is not an end tag token with the tag name
"script", then mark the <code><a href="#script1">script</a></code>
element as "already executed"<!-- XXX xref -->, otherwise, ignore
it. (Marking the <code><a href="#script1">script</a></code> element
as "already executed" prevents it from executing when it is inserted
element as <span><a href="#already">"already executed"</a></span>,
otherwise, the token is the <code><a
href="#script1">script</a></code> element's end tag, so ignore it.
(Marking the <code><a href="#script1">script</a></code> element as
"already executed" prevents it from executing when it is inserted
into the document in the next paragraph.)</p>

<p>Append the new element to the <span><a href="#current3">current
Expand Down Expand Up @@ -23201,13 +23267,12 @@ http://lxr.mozilla.org/mozilla/source/parser/htmlparser/src/nsHTMLTokens.cpp#94
H&aring;kon Wium Lie, James Graham, James Perrett, Jan-Klaas Kollhof,
Jasper Bryant-Greene, Jens Bannmann, Joel Spolsky, Johnny Stenback, Jon
Perlow, Jukka K. Korpela, Kai Hendry, Kornel Lesinski, Lachlan Hunt, Larry
Page, Laurens Holst, L&eacute;onard Bouchet, Maciej Stachowiak, Malcolm
Rowe, Mark Nottingham, Mark Schenk, Martijn Wargers, Martin Honnen,
Matthew Mastracci, Matthew Raymond, Matthew Thomas, Mattias Waldau, Max
Romantschuk, Michael A. Nachbaur, Michael Gratton, Michael 'Ratt'
Iannarelli, Mihai &#x015E;ucan<!--
from ROBO Design -->, Mike Shaver,
Mikko Rantalainen, Neil Deakin, Olav Junker Kj&aelig;r, Rimantas
Page, Laurens Holst, Lenny Domnitser, L&eacute;onard Bouchet, Maciej
Stachowiak, Malcolm Rowe, Mark Nottingham, Mark Schenk, Martijn Wargers,
Martin Honnen, Matthew Mastracci, Matthew Raymond, Matthew Thomas, Mattias
Waldau, Max Romantschuk, Michael A. Nachbaur, Michael Gratton, Michael
'Ratt' Iannarelli, Mihai &#x015E;ucan<!-- from ROBO Design -->, Mike
Shaver, Mikko Rantalainen, Neil Deakin, Olav Junker Kj&aelig;r, Rimantas
Liubertas, Robert O'Callahan, Roman Ivanov, S. Mike Dierken, Shaun Inman,
Simon Pieters, Steven Garrity, Stuart Parmenter, Tantek &Ccedil;elik,
Thomas O'Connor, Tim Altman, Vladimir Vuki&#x0107;evi&#x0107;, and
Expand Down

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