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Check BroadcastChannel origin against creation-time current
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...instead of against the creation-time incumbent. This helps with
#1430, and allows a good amount of simplification as we no longer have
to track the "BroadcastChannel settings object" separately from the
relevant settings object.

This also modernizes and cleans up the BroadcastChannel section
editorially.
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@domenic
domenic committed Jul 10, 2020
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Showing 1 changed file with 44 additions and 52 deletions.
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Expand Up @@ -98150,88 +98150,79 @@ interface <dfn>BroadcastChannel</dfn> : <span>EventTarget</span> {

<div w-nodev>

<p>A <code>BroadcastChannel</code> object has a <dfn>channel name</dfn>, a
<dfn><code>BroadcastChannel</code> settings object</dfn>, and a <dfn
<p>A <code>BroadcastChannel</code> object has a <dfn>channel name</dfn> and a <dfn
data-x="concept-BroadcastChannel-closed">closed flag</dfn>.</p>

<p>The <dfn><code data-x="dom-BroadcastChannel">BroadcastChannel()</code></dfn> constructor, when
invoked, must create and return a <code>BroadcastChannel</code> object whose <span>channel
name</span> is the constructor's first argument, whose <span><code>BroadcastChannel</code>
settings object</span> is the <span>incumbent settings object</span>, and whose <span
data-x="concept-BroadcastChannel-closed">closed flag</span> is false.</p>

<p>The <dfn><code data-x="dom-BroadcastChannel-name">name</code></dfn> attribute must return the
<span>channel name</span>.</p>

<p>The <dfn><code
data-x="dom-BroadcastChannel-postMessage">postMessage(<var>message</var>)</code></dfn> method,
when invoked on a <code>BroadcastChannel</code> object, must run the following steps:</p>
<p>The <dfn><code data-x="dom-BroadcastChannel">new BroadcastChannel(<var>name</var>)</code></dfn>
constructor steps are:</p>

<ol>
<li><p>Let <var>source</var> be this <code>BroadcastChannel</code>.</p></li>
<li><p>Set <span>this</span>'s <span>channel name</span> to <var>name</var>.</p></li>

<li><p>Let <var>sourceSettings</var> be <var>source</var>'s <span><code>BroadcastChannel</code>
settings object</span>.</p></li>
<li><p>Set <span>this</span>'s <span data-x="concept-BroadcastChannel-closed">closed flag</span>
to false.</p></li>
</ol>

<li><p>If <var>source</var>'s <span data-x="concept-BroadcastChannel-closed">closed flag</span>
is true, then throw an <span>"<code>InvalidStateError</code>"</span> <code>DOMException</code>.</p></li>
<p>The <dfn><code data-x="dom-BroadcastChannel-name">name</code></dfn> getter steps are to return
<span>this</span>'s <span>channel name</span>.</p>

<li><p>Let <var>sourceChannel</var> be <var>source</var>'s <span>channel name</span>.</p></li>
<p>The <dfn><code
data-x="dom-BroadcastChannel-postMessage">postMessage(<var>message</var>)</code></dfn> method
steps are:</p>

<li><p>Let <var>targetRealm</var> be an <span>implementation-defined</span> Realm.</p></li>
<ol>
<li><p>If <span>this</span>'s <span data-x="concept-BroadcastChannel-closed">closed flag</span>
is true, then throw an <span>"<code>InvalidStateError</code>"</span>
<code>DOMException</code>.</p></li>

<li><p>Let <var>serialized</var> be <span>StructuredSerialize</span>(<var>message</var>). Rethrow
any exceptions.</p></li>

<li><p>Let <var>sourceOrigin</var> be <span>this</span>'s <span>relevant settings object</span>'s
<span data-x="concept-settings-object-origin">origin</span>.</p></li>

<li>
<p>Let <var>destinations</var> be a list of <code>BroadcastChannel</code> objects that
match the following criteria:</p>

<ul>
<li>
<p>Their <span><code>BroadcastChannel</code> settings object</span> specifies either:</p>
<p>Their <span>relevant global object</span> is either:</p>

<ul>
<li><p>a <span data-x="concept-settings-object-global">global object</span> that is a
<code>Window</code> object whose <span data-x="concept-document-window">associated
<li><p>a <code>Window</code> object whose <span data-x="concept-document-window">associated
<code>Document</code></span> is <span>fully active</span>, or</p></li>

<li><p>a <span data-x="concept-settings-object-global">global object</span> that is a
<code>WorkerGlobalScope</code> object whose <span
<li><p>a <code>WorkerGlobalScope</code> object whose <span
data-x="dom-WorkerGlobalScope-closing">closing</span> flag is false and whose
<span>worker</span> is not a <span>suspendable worker</span>.</p></li>
</ul>
</li>

<li><p>Their <span><code>BroadcastChannel</code> settings object</span>'s <span
<li><p>Their <span>relevant settings object</span>'s <span
data-x="concept-settings-object-origin">origin</span> is <span>same origin</span> with
<var>sourceSettings</var>'s <span
data-x="concept-settings-object-origin">origin</span>.</p></li>
<var>sourceOrigin</var>.</p></li>

<li><p>Their <span>channel name</span> <span>is</span> <var>sourceChannel</var>.</p></li>
<li><p>Their <span>channel name</span> <span>is</span> <span>this</span>'s <span>channel
name</span>.</p></li>
</ul>
</li>

<li><p>Remove <var>source</var> from <var>destinations</var>.</p></li>

<li><p>Sort <var>destinations</var> such that all <code>BroadcastChannel</code> objects whose
<span data-x="BroadcastChannel settings object"><code>BroadcastChannel</code> settings
objects</span> specify the same <span>responsible event loop</span> are sorted in creation
order, oldest first. (This does not define a complete ordering. Within this constraint, user
agents may sort the list in any <span>implementation-defined</span> manner.)</p></li>
<span data-x="relevant agent">relevant agents</span> are the same are sorted in creation order,
oldest first. (This does not define a complete ordering. Within this constraint, user agents may
sort the list in any <span>implementation-defined</span> manner.)</p></li>

<li>
<p>For each <code>BroadcastChannel</code> object <var>destination</var> in
<var>destinations</var>, <span>queue a task</span> on the <span>DOM manipulation task
source</span> of <var>destination</var>'s <span>relevant agent</span>'s <span
data-x="concept-agent-event-loop">event loop</span> that runs the following steps. If that event
loop is a <span>window event loop</span>, then the <span data-x="concept-task">task</span>'s
<span data-x="concept-task-document">document</span> must be set to <var>destination</var>'s
<span><code>BroadcastChannel</code> settings object</span>'s <span>responsible document</span>.</p>
<p>For each <var>destination</var> in <var>destinations</var>, <span>queue a global task</span>
on the <span>DOM manipulation task source</span> given <var>destination</var>'s <span>relevant
global object</span> to perform the following steps:</p>

<ol>
<li><p>If <var>destination</var>'s <span data-x="concept-BroadcastChannel-closed">closed
flag</span> is true, then return.</p></li>
flag</span> is true, then abort these steps.</p></li>

<li><p>Let <var>targetRealm</var> be <var>destination</var>'s <span
data-x="concept-relevant-realm">relevant Realm</span>.</p></li>
Expand All @@ -98244,31 +98235,30 @@ interface <dfn>BroadcastChannel</dfn> : <span>EventTarget</span> {
event</span> named <code data-x="event-messageerror">messageerror</code> at
<var>destination</var>, using <code>MessageEvent</code>, with the <code
data-x="dom-MessageEvent-origin">origin</code> attribute initialized to the <span
data-x="serialization of an origin">serialization</span> of <var>sourceSettings</var>'s <span
data-x="concept-settings-object-origin">origin</span>, and then return.</p>
data-x="serialization of an origin">serialization</span> of <var>sourceOrigin</var>, and then
abort these steps.</p>
</li>

<li><p><span data-x="concept-event-fire">Fire an event</span> named <code
data-x="event-message">message</code> at <var>destination</var>, using
<code>MessageEvent</code>, with the <code data-x="dom-MessageEvent-data">data</code> attribute
initialized to <var>data</var> and the <code data-x="dom-MessageEvent-origin">origin</code>
attribute initialized to the <span data-x="serialization of an origin">serialization</span> of
<var>sourceSettings</var>'s <span
data-x="concept-settings-object-origin">origin</span>.</p></li>
<var>sourceOrigin</var>.</p></li>
</ol>
</li>
</ol>

<p>While a <code>BroadcastChannel</code> object whose <span
data-x="concept-BroadcastChannel-closed">closed flag</span> is false has an event listener
registered for <code data-x="event-message">message</code> events, there must be a strong
reference from <span data-x="concept-settings-object-global">global object</span> specified by
the <code>BroadcastChannel</code> object's <span><code>BroadcastChannel</code> settings
object</span> to the <code>BroadcastChannel</code> object itself.</p>
reference from the <code>BroadcastChannel</code> object's <span>relevant global object</span> to
the <code>BroadcastChannel</code> object itself.</p>

<p>The <dfn><code data-x="dom-BroadcastChannel-close">close()</code></dfn> method must set the
<span data-x="concept-BroadcastChannel-closed">closed flag</span> of the
<code>BroadcastChannel</code> object on which it was invoked to true.</p>
<p>The <dfn><code data-x="dom-BroadcastChannel-close">close()</code></dfn> method steps are to set
<span>this</span>'s <span data-x="concept-BroadcastChannel-closed">closed flag</span> to true.</p>

</div>

<p class="note">Authors are strongly encouraged to explicitly close <code>BroadcastChannel</code>
objects when they are no longer needed, so that they can be garbage collected. Creating many
Expand All @@ -98277,6 +98267,8 @@ interface <dfn>BroadcastChannel</dfn> : <span>EventTarget</span> {
continue to live for as long as they have an event listener (or until their page or worker is
closed).</p>

<div w-nodev>

<hr>

<p>The following are the <span>event handlers</span> (and their corresponding <span data-x="event
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