javascript - 是之间的关系 and it's document one way?</a></h1> <div class="ml12 aside-cta flex--item print:d-none sm:ml0 sm:mb12 sm:order-first sm:as-end"> <a href="https://stackoverflow.com/questions/ask" target="_blank" class="ws-nowrap s-btn s-btnprimary">问问题</a></div> </div> <div class="d-flex fw-wrap pb8 mb16 bb bc-black-075"> <div class="flex--item ws-nowrap mr16 mb8"> <span class="fc-light mr2"></span> </div> <div class="flex--item ws-nowrap mr16 mb8" title="2022-04-17 15:46:40Z"> <span class="fc-light mr2">问问题</span> <time itemprop="dateCreated" datetime="2012-06-28T17:14:38.800">2012-06-28T17:14:38.800</time> </div> <div class="flex--item ws-nowrap mb8" title="Viewed 6 times"> <span class="fc-light mr2"></span> 513 次 </div> </div> <div id="mainbar" role="main" aria-label="question and answers"> <div class="question" data-questionid="4" data-position-on-page="0" data-score="763" id="question"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="4"> <button class="js-vote-up-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-peeufs8c"> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"></path></svg> </button> <div id="--stacks-s-tooltip-peeufs8c" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">This question shows research effort; it is useful and clear<div class="s-popover--arrow"></div></div> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value=""> 3 </div> <button class="js-vote-down-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-04106eqn"> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"></path></svg> </button><div id="--stacks-s-tooltip-04106eqn" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">This question does not show any research effort; it is unclear or not useful<div class="s-popover--arrow"></div></div> <div id="--stacks-s-tooltip-tgvwendx" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">Bookmark this question.<div class="s-popover--arrow"></div></div> <a class="js-post-issue flex--item s-btn s-btnunset c-pointer py6 mx-auto" data-shortcut="T" data-ks-title="timeline" data-controller="s-tooltip" data-s-tooltip-placement="right" aria-label="Timeline" aria-describedby="--stacks-s-tooltip-abwmy15k"><svg aria-hidden="true" class="mln2 mr0 svg-icon iconHistory" width="19" height="18" viewBox="0 0 19 18"><path d="M3 9a8 8 0 1 1 3.73 6.77L8.2 14.3A6 6 0 1 0 5 9l3.01-.01-4 4-4-4h3L3 9Zm7-4h1.01L11 9.36l3.22 2.1-.6.93L10 10V5Z"></path></svg></a><div id="--stacks-s-tooltip-abwmy15k" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">Show activity on this post.<div class="s-popover--arrow"></div></div> </div> </div> <div class="postcell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"> <p>You can get the nodes of the <code>document</code> object of an <code><iframe></code> with the <code>contentDocument</code> property of the <a href="https://developer.mozilla.org/en/DOM/HTMLIFrameElement" rel="nofollow"><code>HTMLIFrameElement</code></a></p>

<p>But I can't find a way getting the <code><iframe></code> back out of the node.<br>
Is the relation between the <code><iframe></code> and it's document is only one way?<br>
If it does, <strong>WHY?</strong></p>

<p><a href="http://jsfiddle.net/DjSec/" rel="nofollow">A non working DEMO:</a></p>

<pre><code>var iframe = document.getElementById('iframe');
var doc = iframe.contentDocument || iframe.contentWindow.document;

var div = doc.getElementsByTagName('div')[0];

console.log('Did we find the iframe? ' + ($(div).closest('iframe').length > 0));
// Output: "Did we find the iframe? false"
</code></pre>
 </div> <div class="mt24 mb12"> <div class="post-taglist d-flex gs4 gsy fd-column"> <div class="d-flex ps-relative fw-wrap"> <a href="/tags/javascript" class="post-tag js-gps-track" title="show questions tagged 'javascript'" rel="tag">javascript</a><a href="/tags/jquery" class="post-tag js-gps-track" title="show questions tagged 'jquery'" rel="tag">jquery</a><a href="/tags/dom" class="post-tag js-gps-track" title="show questions tagged 'dom'" rel="tag">dom</a><a href="/tags/iframe" class="post-tag js-gps-track" title="show questions tagged 'iframe'" rel="tag">iframe</a><a href="/tags/dom-traversal" class="post-tag js-gps-track" title="show questions tagged 'dom-traversal'" rel="tag">dom-traversal</a> </div> </div> </div> </div> <span class="d-none" itemprop="commentCount">4</span> </div> </div> <div class="js-zone-container zone-container-responsive"> <div id="dfp-isb" class="everyonelovesstackoverflow everyonelovesinline-sidebar mx-auto" style="min-height: auto; height: auto; display: none;"></div> <div class="js-report-ad-button-container mx-auto" style="width: 300px"></div> </div> <div id="answers"> <a name="tab-top"></a> <div id="answers-header"> <div class="answers-subheader d-flex ai-center mb8"> <div class="flex--item fl1"> <h2 class="mb0" data-answercount=""> 2 回答 <span style="display:none;" itemprop="answerCount">2</span> </h2> </div> </div> </div> <a name="7"></a> <div id="answer-7" class="answer js-answer accepted-answer" data-answerid="7" data-parentid="4" data-score="506" data-position-on-page="1" data-highest-scored="1" data-question-has-accepted-highest-score="1" itemprop="suggestedAnswer" itemscope="" itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="7"> <button class="js-vote-up-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-dgvag2l3"> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"></path></svg> </button><div id="--stacks-s-tooltip-dgvag2l3" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">This answer is useful<div class="s-popover--arrow"></div></div> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="5"> 5 </div> <button class="js-vote-down-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-gn8ppsfv"> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"></path></svg> </button> </div> </div> <div class="answercell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"> <p>The <code>iframe</code> element is in different <code>document</code> (it's an element in the main page) than the <code>div</code> element (it's an element in the iframe page). </p>

<p>You can get the <code>iframe</code> element like this:</p>

<p><code>iframe.contentWindow.frameElement === iframe</code></p>

<p>Or when inside the <code>iframe</code> script environment:</p>

<p><code>window.frameElement</code></p>

<p>Or using the <code>div</code></p>

<p><code>div.ownerDocument.defaultView.frameElement === iframe</code></p>

<p><a href="http://jsfiddle.net/DjSec/3/" rel="noreferrer">Updated demo</a></p>
 </div> <div class="mt24"> <div class="user-action-time" style="color:#999;text-align:right;">于 2012-06-28T17:21:45.020 回答</div> </div> </div> </div> </div><a name="7"></a> <div id="answer-7" class="answer js-answer accepted-answer" data-answerid="7" data-parentid="4" data-score="506" data-position-on-page="1" data-highest-scored="1" data-question-has-accepted-highest-score="1" itemprop="suggestedAnswer" itemscope="" itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="7"> <button class="js-vote-up-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-dgvag2l3"> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"></path></svg> </button><div id="--stacks-s-tooltip-dgvag2l3" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">This answer is useful<div class="s-popover--arrow"></div></div> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="0"> 0 </div> <button class="js-vote-down-btn flex--item s-btn s-btn__unset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-gn8ppsfv"> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"></path></svg> </button> </div> </div> <div class="answercell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"> <p>thing is, for <code>(div)</code> in the <code>console.log</code> line, they are part of the frame, they don't know they are in a frame so <code>.closest('iframe')</code> will be empty. </p>
 </div> <div class="mt24"> <div class="user-action-time" style="color:#999;text-align:right;">于 2012-06-28T17:19:18.760 回答</div> </div> </div> </div> </div></div> </div> <div id="sidebar" class="show-votes" role="complementary" aria-label="sidebar"> <div class="module sidebar-related"> <h4 id="h-related">Related</h4> <div class="related js-gps-related-questions" data-tracker="rq=1"> <div class="spacer"> <a href="/questions/10854429" title="Question score (upvotes - downvotes)"> <div class="answer-votes large">2</div> </a> <a href="/questions/10854429" class="question-hyperlink">iphone - Unrar4iOS 错误，File::tell() 抛出 asm 代码，我该怎么办？</a> </div><div class="spacer"> <a href="/questions/10854431" title="Question score (upvotes - downvotes)"> <div class="answer-votes large">2</div> </a> <a href="/questions/10854431" class="question-hyperlink">jquery - 如何：单击标记时 - 使地图变暗并在地图顶部显示一个大 div 而不是带有信息的信息框</a> </div><div class="spacer"> <a href="/questions/10854432" title="Question score (upvotes - 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