From 3fb0aa62a96f0b3a8afb016ca95a805ccd3fc5b0 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Sat, 10 Jun 2023 01:00:34 -0700
Subject: [PATCH] Handle attribute changes after changing attribute

In all implementations, internal listeners for attribute changes which are run as "attribute change steps" are run after the attribute is actually changed, not before.

This affects popover attribute related algorithms in HTML: https://github.com/whatwg/html/pull/9048#discussion_r1141122175.
---
 dom.bs | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/dom.bs b/dom.bs
index 6dab94dcd..86d98eb58 100644
--- a/dom.bs
+++ b/dom.bs
@@ -6297,10 +6297,10 @@ given a <var>document</var>, <var>localName</var>, <var>namespace</var>, and opt
 <a>attribute</a> <var>attribute</var> to <var>value</var>, run these steps:
 
 <ol>
+ <li><p>Set <var>attribute</var>'s <a for=Attr>value</a> to <var>value</var>.
+
  <li><p><a>Handle attribute changes</a> for <var>attribute</var> with <var>attribute</var>'s
  <a for=Attr>element</a>, <var>attribute</var>'s <a for=Attr>value</a>, and <var>value</var>.
-
- <li><p>Set <var>attribute</var>'s <a for=Attr>value</a> to <var>value</var>.
 </ol>
 
 <p>To <dfn export id=concept-element-attributes-append lt="append an attribute">append</dfn> an
@@ -6308,36 +6308,34 @@ given a <var>document</var>, <var>localName</var>, <var>namespace</var>, and opt
 steps:
 
 <ol>
- <li><p><a>Handle attribute changes</a> for <var>attribute</var> with <var>element</var>, null, and
- <var>attribute</var>'s <a for=Attr>value</a>.
-
  <li><p><a for=list>Append</a> <var>attribute</var> to <var>element</var>'s
  <a for=Element>attribute list</a>.
 
  <li><p>Set <var>attribute</var>'s <a for=Attr>element</a> to <var>element</var>.
+
+ <li><p><a>Handle attribute changes</a> for <var>attribute</var> with <var>element</var>, null, and
+ <var>attribute</var>'s <a for=Attr>value</a>.
 </ol>
 
 <p>To <dfn export id=concept-element-attributes-remove lt="remove an attribute">remove</dfn> an
 <a>attribute</a> <var>attribute</var>, run these steps:
 
 <ol>
- <li><p><a>Handle attribute changes</a> for <var>attribute</var> with <var>attribute</var>'s
- <a for=Attr>element</a>, <var>attribute</var>'s <a for=Attr>value</a>, and null.
+ <li><p>Let <var>element</var> be <var>attribute</var>'s <a for=Attr>element</a>.</p></li>
 
- <li><a for=list>Remove</a> <var>attribute</var> from <var>attribute</var>'s
- <a for=Attr>element</a>'s <a for=Element>attribute list</a>.
+ <li><a for=list>Remove</a> <var>attribute</var> from <var>element</var>'s <a for=Element>attribute
+ list</a>.
 
  <li><p>Set <var>attribute</var>'s <a for=Attr>element</a> to null.
+
+ <li><p><a>Handle attribute changes</a> for <var>attribute</var> with <var>element</var>,
+ <var>attribute</var>'s <a for=Attr>value</a>, and null.
 </ol>
 
 <p>To <dfn export id=concept-element-attributes-replace lt="replace an attribute">replace</dfn> an
 <a>attribute</a> <var>oldAttr</var> with an <a>attribute</a> <var>newAttr</var>, run these steps:
 
 <ol>
- <li><p><a>Handle attribute changes</a> for <var>oldAttr</var> with <var>oldAttr</var>'s
- <a for=Attr>element</a>, <var>oldAttr</var>'s <a for=Attr>value</a>, and <var>newAttr</var>'s
- <a for=Attr>value</a>.
-
  <li><p><a for=list>Replace</a> <var>oldAttr</var> by <var>newAttr</var> in <var>oldAttr</var>'s
  <a for=Attr>element</a>'s <a for=Element>attribute list</a>.
 
@@ -6345,6 +6343,10 @@ steps:
  <a for=Attr>element</a>.
 
  <li><p>Set <var>oldAttr</var>'s <a for=Attr>element</a> to null.
+
+ <li><p><a>Handle attribute changes</a> for <var>oldAttr</var> with <var>newAttr</var>'s
+ <a for=Attr>element</a>, <var>oldAttr</var>'s <a for=Attr>value</a>, and <var>newAttr</var>'s
+ <a for=Attr>value</a>.
 </ol>
 
 <hr>