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<h4>Processing model</h4>

<p>A user interaction <dfn data-x="activates-a-window">activates a <code>Window</code> object
<var>W</var></dfn> if either:</p>
<ul>
<li>input events from the user interaction is targetted to an element of <var>W</var>, or</li>

<li>the interaction <span data-x="activates-a-window">activates the <code>Window</code>
object</span> in a subframe of <var>W</var>.</li>
</ul>
<p>When a user interaction in a <span>browsing context</span> <var>B</var> causes firing of an <a
href="#activation-triggering-event">activation triggering input events</a> in that context, it
<dfn data-x="activate-window">activates the <code>Window</code> objects</dfn> in all <span
data-x="ancestor browsing context">ancestor browsing contexts</span> of <var>B</var> (including
the one in <var>B</var> itself).</p>

<p>The <dfn>user activation state</dfn> of a <code>Window</code> object <var>W</var> consists of
two boolean flags, both of which are initially set to false:</p>

<ul>
<li>The <dfn>sticky activation flag</dfn> indicates the historical activation state: whether the
user has ever interacted with <var>W</var> or its subframes. The flag is set when <var>W</var>
is <span data-x="activates-a-window">activated</span> for the very first time, and is never
reset during the lifetime of <var>W</var>.</li>

<li>The <dfn>transient activation flag</dfn> indicates the current activation state: whether the
user is currently interacting with <var>W</var> or its subframes. The flag is set every time
<var>W</var> is <span data-x="activates-a-window">activated</span>, and is reset either
<ul>
<li>after an expiry time defined by the browser, or</li>
<li>through a call to an <span data-x="">activation-consuming API</span> in the context of
any <code>Window</code> object of the page.</li>
</ul>
</li>

<li><p>The <dfn>sticky activation flag</dfn> indicates the historical activation state: whether
the user has ever interacted with <var>W</var> or its subframes. When <var>W</var> is <span
data-x="activate-window">activated</span> for the very first time, the UA sets the flag to true.
This flag is never set to false during the lifetime of <var>W</var>.</p></li>

<li><p>The <dfn>transient activation flag</dfn> indicates the current activation state: whether
the user is currently interacting with <var>W</var> or its subframes. Every time <var>W</var> is
<span data-x="activate-window">activated</span>, the UA sets the flag to true. The UA sets the
flag to false when the flag either <span data-x="expiration of transient
activation">expires</span> or gets <span data-x="consumption of transient
activation">consumed</span>.</p></li>

</ul>

<p class="note"> The propagation of the <span>transient activation flag</span> in the frame tree
is assymetric between setting vs resetting of the flag. A user interaction with a frame
<var>F</var> sets the flag in the <code>Window</code> object of each ancestor frame of
<var>F</var> (including <var>F</var> itself). However, an <span data-x="">activation-consuming
API</span> call in the context of the <code>Window</code> object of frame of <var>F</var> resets
the flag in <em>all</em> <code>Window</code> objects across the whole frame tree. This prevents
multiple calls to an <span data-x="">activation-consuming API</span> even when the frame hierarchy
is deep.</p>
<dl>

<dt><dfn>Expiration of transient activation</dfn></dt>

<dd>

<p>The UA sets the <span>transient activation flag</span> to false after a UA-defined expiry
time has elapsed since the last time <var>W</var> was
<span data-x="activate-window">activated</span>.</p>

<p class="note">The expiry time has to be at most a few seconds so that the user can possibly
perceive the link between an interaction with a page and the page opening a popup, for
example.</p>

<p class="note">The UA can possibly implement the expiration of <span>transient activation
flag</span> through time-stamping: the UA would have an internal time-stamp field in <span>user
activation state</span> which is updated to current time-stamp every time <var>W</var> is
<span data-x="activate-window">activated</span>. Then every time the <span>transient activation
flag</span> is checked, the UA would return true iff current time-stamp is less than the stored
time-stamp plus the expiry time.</p>

</dd>

<dt><dfn>Consumption of transient activation</dfn><dt>

<dd>

<p>The UA sets the <span>transient activation flag</span> to whenever any script in the page
makes a call to an <span>activation consuming API</span> such as <code
data-x="dom-open">window.open()</code>.</p>

<p class="note" w-nodev>Note the assymetry between setting the <span>transient activation
flag</span> to true and false from the perspective of the <span data-x="browsing
context">browsing contexts</span> of the page. A user interaction with a <code>Window</code>
object <var>W</var> sets to true the transient activation flags in only the <span
data-x="ancestor browsing context">ancestor browsing contexts</span> of <var>W</var>. However,
a consumping in <var>W</var> sets to false the flags in all browsing contexts of the page (more
precisely, all <span data-x="list of the descendant browsing contexts">descendant browsing
contexts</span> of the <span>top-level browsing context</span> of <var>W</var>). Consuming the
flag in this manner prevents malicious sites from making multiple calls to an <span>activation
consuming API</span> from a single user activation (possibly by exploiting a deep hierarchy of
browsing contexts).</p>

</dd>

</dl>

<h4>APIs gated by user activation</h4>

<p>APIs that are dependent on <span>user activation state</span> are classified into three
different levels. The levels are as follows, sorted by their "strength of dependence" on user
activation (from strongest to weakest):</p>
<ol>
<li><dfn>Transient activation consuming APIs</dfn>: These APIs require the transient bit, and
they consume the bit in each call to prevent multiple calls per user activation.</li>
<dl>
<dt><dfn data-x="activation consuming api">Transient activation consuming APIs</dfn></dt>

<li><dfn>Transient activation gated APIs</dfn>: These APIs require the transient bit but don't
consume it, so multiple calls are allowed per user activation until the transient bit
expires.</li>
<dd><p>These APIs require the transient activation flag to be true, and they <span
data-x="consumption of transient activation">consume</span> the flag in each call to prevent multiple
calls per user activation.</p></dd>

<li><dfn>Sticky activation gated APIs</dfn>: These APIs require the sticky activation bit, so
they are blocked until the very first user activation.</li>
</ol>
<dt><dfn data-x="transient activation gated api">Transient activation gated APIs</dfn><dt>

<dd><p>These APIs require the transient activation flag to be true but don't consume it, so
multiple calls are allowed per user activation until the transient bit <span data-x="expiration
of transient activation">expires</span>.</p></dd>

<dt><dfn data-x="sticky activation gated api">Sticky activation gated APIs</dfn></dt>

<dd><p>These APIs require the sticky activation flag to be true, so they are blocked
until the very first user activation.</p></dd>

</dl>


<h4>Events triggering user activation</h4>
<h4 id="activation-triggering-event">Input events triggering user activation</h4>

<div w-nodev>

Expand All @@ -72571,15 +72614,15 @@ END:VCARD</pre>
data-x="dom-Event-isTrusted">isTrusted</code> attribute is true and whose <code
data-x="dom-Event-type">type</code> is one of:</p>
<ul class="brief">
<li><code data-x="event-change">change</code></li>
<li><code data-x="event-click">click</code></li>
<li><code data-x="event-contextmenu">contextmenu</code></li>
<li><code data-x="event-dblclick">dblclick</code></li>
<li><code data-x="event-mouseup">mouseup</code></li>
<li><code data-x="event-pointerup">pointerup</code></li>
<li><code data-x="event-reset">reset</code></li>
<li><code data-x="event-submit">submit</code></li>
<li><code data-x="event-touchend">touchend</code></li>
<li><code data-x="event-change">change</code></li>
<li><code data-x="event-click">click</code></li>
<li><code data-x="event-contextmenu">contextmenu</code></li>
<li><code data-x="event-dblclick">dblclick</code></li>
<li><code data-x="event-mouseup">mouseup</code></li>
<li><code data-x="event-pointerup">pointerup</code></li>
<li><code data-x="event-reset">reset</code></li>
<li><code data-x="event-submit">submit</code></li>
<li><code data-x="event-touchend">touchend</code></li>
</ul>

</div>
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