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Remove the inert document from the HTML fragment parsing algorithm #11970

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57a1873
Remove the inert document from the HTML fragment parser
foolip Nov 28, 2025
46d394f
Add a target argument to the HTML/XML fragment parsing algorithms
foolip Nov 28, 2025
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91 changes: 35 additions & 56 deletions source
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Original file line number Diff line number Diff line change
Expand Up @@ -123842,17 +123842,11 @@ enum <dfn enum>DOMParserSupportedType</dfn> {
<var>html</var>:</p>

<ol>
<li><p>Let <var>newChildren</var> be the result of the <span>HTML fragment parsing
algorithm</span> given <var>contextElement</var>, <var>html</var>, and true.</p></li>

<li><p>Let <var>fragment</var> be a new <code>DocumentFragment</code> whose <span>node
document</span> is <var>contextElement</var>'s <span>node document</span>.</p></li>

<li><p>For each <var>node</var> in <var>newChildren</var>, <span
data-x="concept-node-append">append</span> <var>node</var> to <var>fragment</var>.</p></li>
<li><p><span data-x="concept-node-remove">Remove</span> all <var>target</var>'s <span
data-x="concept-tree-child">children</span>, in <span>tree order</span>.</p></li>

<li><p><span data-x="concept-node-replace-all">Replace all</span> with <var>fragment</var> within
<var>target</var>.</p></li>
<li><p>Run the <span>HTML fragment parsing algorithm</span> given <var>target</var>,
<var>contextElement</var>, <var>html</var>, and true.</p></li>
</ol>
</div>

Expand Down Expand Up @@ -123997,25 +123991,17 @@ enum <dfn enum>DOMParserSupportedType</dfn> {
<var>context</var> and a string <var>markup</var>, are:</p>

<ol>
<li><p>Let <var>fragment</var> be a new <code>DocumentFragment</code> whose <span>node
document</span> is <var>context</var>'s <span>node document</span>.</p></li>

<li><p>Let <var>algorithm</var> be the <span>HTML fragment parsing algorithm</span>.</p></li>

<li><p>If <var>context</var>'s <span>node document</span> is an <span data-x="XML documents">XML
document</span>, then set <var>algorithm</var> to the <span>XML fragment parsing
algorithm</span>.</p></li>

<li><p>Let <var>newChildren</var> be the result of invoking <var>algorithm</var> given
<var>context</var> and <var>markup</var>.</p></li>

<li><p>Let <var>fragment</var> be a new <code>DocumentFragment</code> whose <span>node
document</span> is <var>context</var>'s <span>node document</span>.</p></li>

<li>
<p>For each <var>node</var> of <var>newChildren</var>, in <span>tree order</span>: <span
data-x="concept-node-append">append</span> <var>node</var> to <var>fragment</var>.</p>

<p class=note>This ensures the <span>node document</span> for the new <span
data-x="node">nodes</span> is correct.</p>
</li>
<li><p>Invoke <var>algorithm</var> given <var>fragment</var>, <var>context</var> and
<var>markup</var>.</p></li>

<li><p>Return <var>fragment</var>.</p></li>
</ol>
Expand Down Expand Up @@ -144509,10 +144495,11 @@ console.assert(container.firstChild instanceof SuperP);
<h3>Parsing HTML fragments</h3>

<div algorithm>
<p>The <dfn>HTML fragment parsing algorithm</dfn>, given an <code>Element</code> node <dfn
data-x="concept-frag-parse-context"><var>context</var></dfn>, string <var>input</var>, and an
optional boolean <var>allowDeclarativeShadowRoots</var> (default false) is the following steps.
They return a list of zero or more nodes.</p>
<p>The <dfn>HTML fragment parsing algorithm</dfn>, given an <code>Element</code> or
<code>DocumentFragment</code> <var>target</var>, an <code>Element</code> <dfn
data-x="concept-frag-parse-context"><var>context</var></dfn>, a string <var>input</var>, and an
optional boolean <var>allowDeclarativeShadowRoots</var> (default false) is the following
steps. Zero or more nodes are inserted into <var>target</var>.</p>

<p class="note">Parts marked <dfn>fragment case</dfn> in algorithms in the <span>HTML
parser</span> section are parts that only occur if the parser was created for the purposes of this
Expand All @@ -144522,22 +144509,13 @@ console.assert(container.firstChild instanceof SuperP);
handling this algorithm, then that is an error in the specification.</p>

<ol>
<li><p>Let <var>document</var> be a <code>Document</code> node whose <span
data-x="concept-document-type">type</span> is "<code data-x="">html</code>".</p></li>
<li><p>Let <var>parser</var> be a new <span>HTML parser</span> associated with
<var>context</var>'s <span>node document</span>.</p></li>
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@annevk annevk Dec 1, 2025

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This seems wrong as this would mean the parser will potentially manipulate that document. Though exactly how this is layered today is unclear.

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@foolip foolip Dec 1, 2025

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Here are the bits that I could find beyond inserting nodes:

I'll have to check how implementations deal with these cases.


<li><p>If <var data-x="concept-frag-parse-context">context</var>'s <span>node document</span> is
in <span>quirks mode</span>, then set <var>document</var>'s <span
data-x="concept-document-mode">mode</span> to "<code data-x="">quirks</code>".</p></li>
<li><p>Set <var>parser</var>'s TODO target to <var>target</var>.</p></li>

<li><p>Otherwise, if <var data-x="concept-frag-parse-context">context</var>'s <span>node
document</span> is in <span>limited-quirks mode</span>, then set <var>document</var>'s <span
data-x="concept-document-mode">mode</span> to "<code data-x="">limited-quirks</code>".</p></li>

<li><p>If <var>allowDeclarativeShadowRoots</var> is true, then set <var>document</var>'s <span
data-x="concept-document-allow-declarative-shadow-roots">allow declarative shadow roots</span> to
true.</p></li>

<li><p>Create a new <span>HTML parser</span>, and associate it with <var>document</var>.</p></li>
<li><p>If <var>allowDeclarativeShadowRoots</var> is true, then set <var>parser</var>'s
TODO <!-- https://github.com/whatwg/html/pull/11965 --> to true.</p></li>

<li>
<p>Set the state of the <span>HTML parser</span>'s <span>tokenization</span> stage as
Expand Down Expand Up @@ -144577,16 +144555,18 @@ console.assert(container.firstChild instanceof SuperP);
transitions.</p>
</li>

<li><p>Let <var>root</var> be the result of <span data-x="create an element">creating an
element</span> given <var>document</var>, "<code data-x="">html</code>", the <span>HTML
namespace</span>, null, null, false, and <var>context</var>'s <span
data-x="element-custom-element-registry">custom element registry</span>.</p></li>
<li><p>Set up the <span>HTML parser</span>'s <span>stack of open elements</span> so that it
contains just the single node (maybe not element!) <var>target</var>.</p></li>

<li><p><span data-x="concept-node-append">Append</span> <var>root</var> to
<var>document</var>.</p></li>
<!--
Chromium puts the DocumentFragment as the first item on the stack of open elements:
https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/html/parser/html_tree_builder.cc;l=339-344;drc=f94df6678b9dba1f9faf292374830260cc90ae54

<li><p>Set up the <span>HTML parser</span>'s <span>stack of open elements</span> so that it
contains just the single element <var>root</var>.</p></li>
So does WebKit:
https://github.com/WebKit/WebKit/blob/8ffda356226982423d22448a9c656a060773cd73/Source/WebCore/html/parser/HTMLTreeBuilder.cpp#L282-L284

What does Gecko do?
-->

<li><p>If <var data-x="concept-frag-parse-context">context</var> is a <code>template</code>
element, then push "<span data-x="insertion mode: in template">in template</span>" onto the
Expand Down Expand Up @@ -144624,9 +144604,6 @@ console.assert(container.firstChild instanceof SuperP);

<li><p>Start the <span>HTML parser</span> and let it run until it has consumed all the characters
just inserted into the input stream.</p></li>

<li><p>Return <var>root</var>'s <span data-x="concept-tree-child">children</span>, in <span>tree
order</span>.</p></li>
</ol>
</div>

Expand Down Expand Up @@ -144952,9 +144929,10 @@ console.assert(container.firstChild instanceof SuperP);
<h3 id="parsing-xhtml-fragments">Parsing XML fragments</h3>

<div algorithm>
<p>The <dfn>XML fragment parsing algorithm</dfn> given an <code>Element</code> node <var
<p>The <dfn>XML fragment parsing algorithm</dfn> given an <code>Element</code> or
<code>DocumentFragment</code> <var>target</var>, <code>Element</code> node <var
data-x="concept-frag-parse-context">context</var> and a string <var>input</var>, runs the
following steps. They return a list of nodes.</p>
following steps. Zero or more nodes are inserted into <var>target</var>.</p>

<ol>
<li><p>Create a new <span>XML parser</span>.</p></li>
Expand Down Expand Up @@ -144989,8 +144967,9 @@ console.assert(container.firstChild instanceof SuperP);
<!-- This is technically redundant, but apparently it has gone wrong in the past:
https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=1443 -->

<li><p>Return the resulting <code>Document</code> node's <span>document element</span>'s <span
data-x="concept-tree-child">children</span>, in <span>tree order</span>.</p></li>
<li><p><span data-x="concept-node-append">Append</span> the resulting <code>Document</code>
node's <span>document element</span>'s <span data-x="concept-tree-child">children</span> to
<var>target</var>, in <span>tree order</span>.</p></li>
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@annevk annevk Dec 1, 2025

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This will create the wrong mutation records.

</ol>
</div>

Expand Down