我在这里使用了一个带有click事件的按钮来添加新元素，但是您可以（应该？）使用一个mutation observer来监听DOM更改，如下所示：Determining if a HTML element has been added to the DOM dynamically参考：https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver
所以我添加了点击按钮的元素，然后启动了在变异观察器中添加事件处理程序（可能需要您的设置）的方法;
超级冗长和大量的日志记录，但应该告诉你如何开始在这里。
注意：由于新元素在添加时会隐藏，所以我只是简单地记录了这些元素以显示它们的存在。

const addMenuButton = document.querySelector("#add-menus");
/* Or any other selector or method to get the element; this makes assumptions here
 * I just put it after an existing element I saw; it just has to exist.
 */
//const somethingTarget = document.querySelector(".docs-loading-indicator");
//my random pick of something actual that exists: 
const somethingTarget = addMenuButton; //document.querySelector(".punch-viewer-speakernotes");

//console.log(somethingTarget);
function addNewListener() {
  // Or any other selector or method to get the element; this makes assumptions here
  const goofyTargetContainer = document.querySelector(".button-container");
  console.log(goofyTargetContainer);
  if (goofyTargetContainer) {
    const goofyTarget = goofyTargetContainer.querySelector(".goog-menu");
    console.log("Proof it is there:", goofyTarget);
    // Do something with `goofyTarget` like find the menu items and add a listener
    goofyTarget.querySelectorAll('.goog-menuitem').forEach(function(menuElement) {
      console.log(menuElement.id);
      console.log(menuElement.innerHTML);
      menuElement.addEventListener("click", function(event) {
        console.log(event.target.id);
      });
    });
  } else {
    console.log('It does not exist yet');
  }

  // Later, you can stop observing
  observer.disconnect();
}
/* just to show the delay add these are added on the button click 
 * This could also be a document change sniff or some event that indicates the elements
 * are now present. I simply use a button for this example and added a second click handler to it.
 */

addMenuButton.addEventListener("click", function(event) {
  const newContent = `<div class="goog-menu goog-menu-vertical" role="listbox" aria-haspopup="true" style="user-select: none; visibility: visible; overflow-y: auto; height: 628px; left: 17.9861px; top: 0px; box-sizing: border-box; width: 898px; display: none;">
<div class="goog-menuitem googoption" role="menuitemradio" id=":2c">Option 1</div>
<div class="goog-menuitem googoption" role="menuitemradio" id=":2d">Option 2</div>
<div class="goog-menuitem googoption" role="menuitemradio" id=":2e">Option 3</div>
<div class="goog-menuitem googoption" role="menuitemradio" id=":2g">Option 4</div>
<div class="goog-menuitem googoption" role="menuitemradio" id=":2h">Option 5</div>
</div>`;
  somethingTarget.insertAdjacentHTML("afterend", newContent);
  // call the listener
  console.log('Adding listener now');
  event.target.innerHTML = "Fired on click to add the 'menu' options";

  // options: only fires one time and is dispatched before any other and will never call preventDefault()
}, {
  once: true,
  capture: true,
  passive: true
});

// Select the node that will be observed for mutations
const targetNode = document.getElementById('button-container-id');

// Options for the observer (which mutations to observe)
const config = {
  attributes: true,
  childList: true,
  subtree: true
};

// Callback function to execute when mutations are observed
const callback = (mutationList, observer) => {
  console.log('mutation observed');
  for (const mutation of mutationList) {
    console.log("Mutation:", mutation.type);
    if (mutation.type === 'childList') {
      console.log('A child node has been added or removed.');
      addNewListener();
    } else if (mutation.type === 'attributes') {
      console.log(`The ${mutation.attributeName} attribute was modified.`);
    }
  }
};

// Create an observer instance linked to the callback function
const observer = new MutationObserver(callback);

// Start observing the target node for configured mutations
observer.observe(targetNode, config);

.button-container {
  padding: 1rem;
  border: solid 1px green;
}

<div id="button-container-id" class="button-container"><button type="button" id="add-menus">Just to show delay. Click to add menus for test</button></div>
<div id="punch-viewer-speakernotes">
  <table class="punch-viewer-speakernotes punch-viewer-client-rendered-notes">
    <tbody>
      <tr>
        <td class="punch-viewer-speakernotes-side-panel" style="width: 331px;">
          <div class="punch-viewer-speakernotes-timer-panel">
            <div class="punch-viewer-speakernotes-timer-main-container">
              <div class="punch-viewer-speakernotes-timer-time-container" style="">
                <div class="punch-viewer-speakernotes-timer-time">00:00:25</div>
              </div>
              <div class="punch-viewer-speakernotes-timer-button-container">
                <div role="button" class="jfk-button jfk-button-standard punch-viewer-speakernotes-timer-button" tabindex="0" title="Pause timer" value="undefined" style="user-select: none; width: 54px;"><span class="jfk-button-label">Pause</span></div>
                <div role="button" class="jfk-button jfk-button-standard punch-viewer-speakernotes-timer-button" tabindex="0" title="Reset timer (R)" value="undefined" style="user-select: none; width: 54px;"><span class="jfk-button-label">Reset</span></div>
              </div>
            </div>
          </div>
          <div class="punch-viewer-speakernotes-page-control-panel">
            <div class="punch-viewer-speakernotes-page-control">
              <div class="goog-inline-block goog-flat-menu-button jfk-select" role="listbox" aria-expanded="false" tabindex="0" aria-haspopup="true" aria-activedescendant=":39" style="user-select: none;">
                <div class="goog-inline-block goog-flat-menu-button-caption" id=":39" role="option" aria-selected="true" aria-setsize="29" aria-posinset="5">Slide 5 </div>
                <div class="goog-inline-block goog-flat-menu-button-dropdown" aria-hidden="true">&nbsp;</div>
              </div>
              <div class="punch-viewer-speakernotes-page-container" style="width: 291px; height: 164px;">
                <div class="punch-viewer-speakernotes-page" style="width: 291px; height: 164px;">
                  <div class="punch-viewer-loadstatus" style="display: none;">
                    <div class="punch-viewer-center punch-viewer-center-browser-modern punch-viewer-center-boxtype-all">
                      <div class="punch-viewer-center-content-container"><span class="punch-viewer-center-centering"></span>
                        <div class="punch-viewer-loadstatus-content goog-inline-block punch-viewer-center-content">
                          <div class="" style="display: none;"></div>
                          <div class="" style="display: none;"></div>
                          <div class="" style="display: none;"></div>
                          <div><span tabindex="0" class="punch-viewer-loadstatus-link" style="display: none;"></span><span tabindex="0" class="punch-viewer-loadstatus-link" style="display: none;"></span></div>
                        </div>
                      </div>
                    </div>
                  </div><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" fill-rule="evenodd" fill="none" stroke="none" stroke-linecap="square" stroke-miterlimit="10" overflow="hidden" preserveAspectRatio="none"
                    width="100%" height="100%" viewBox="0 0 365760 205740" style="line-height: normal; width: 291px; height: 164px;">
                                        <rect fill="#ffffff" fill-opacity="0" width="100%" height="100%"></rect>
                                        <g transform="translate(0 0) scale(1)">
                                            <defs cursor="default"></defs>
                                            <g>
                                                <path fill="#fff" fill-opacity="1" d="M 0 0 L 365760 0 365760 205740 0 205740 Z"></path>
                                                <g id="g1e02d4ec510_1_0-bg">
                                                    <g>
                                                        <g>
                                                            <path fill="#FF9900" fill-opacity="1" d="M 0 0 L 365760 0 365760 205740 0 205740 Z"></path>
                                                        </g>
                                                    </g>
                                                </g>
                                                <g id="g1e02d4ec510_1_1">
                                                    <g>
                                                        <g>
                                                            <path d="M 2041 0 L 367801 0 367801 205740 2041 205740 Z"></path>
                                                        </g>
                                                        <g>
                                                            <g direction="ltr">
                                                                <g transform="matrix(380.99999999999994,0,0,380.99999999999994,5698,75438)">
                                                                    <g pointer-events="none">
                                                                        <g id="g1e02d4ec510_1_1-paragraph-0">
                                                                            <g>
                                                                                <g class="sketchy-text-background" visibility="visible"></g>
                                                                                <g></g>
                                                                                <g class="sketchy-text-content" visibility="visible">
                                                                                    <g class="sketchy-text-content-text" transform="translate(0 115.19999999999999)"><text style="font-family:Arial;font-size:120px;fill:#595959;white-space:pre;" text-rendering="geometricPrecision" x="437.02657480314963">4</text></g>
                                                                                </g>
                                                                            </g>
                                                                        </g>
                                                                    </g>
                                                                </g>
                                                            </g>
                                                        </g>
                                                    </g>
                                                </g>
                                            </g>
                                        </g>
                                    </svg>
                </div>
              </div>
              <div role="button" tabindex="0" class="punch-viewer-speakernotes-page-previous" style="width: 131px; border-width: 1px;"><iframe class="punch-viewer-speakernotes-page-iframe" frameborder="0" tabindex="-1" style="width: 129px; height: 73px;"></iframe>
                <div class="punch-viewer-speakernotes-page-caption">Previous</div>
              </div>
              <div role="button" tabindex="0" class="punch-viewer-speakernotes-page-next" style="width: 131px; border-width: 1px;"><iframe class="punch-viewer-speakernotes-page-iframe" frameborder="0" tabindex="-1" style="width: 129px; height: 73px;"></iframe>
                <div class="punch-viewer-speakernotes-page-caption">Next</div>
              </div>
            </div>
          </div>
        </td>
        <td class="punch-viewer-speakernotes-main-panel punch-viewer-speakernotes-qanda">
          <div class="goog-tab-bar goog-tab-bar-horizontal goog-tab-bar-top" role="tablist" style="user-select: none;">
            <div class="goog-tab" role="tab" aria-selected="false" tabindex="0" id=":2a" style="user-select: none;">Audience tools
              <div aria-live="polite" role="status">
                <div class="docs-offscreen-z-index"></div>
                <div class="punch-viewer-speaker-questions-badge" style="display: none;"></div>
              </div>
            </div>
            <div class="goog-tab goog-tab-selected" role="tab" aria-selected="true" tabindex="0" id=":2b" style="user-select: none;">Speaker notes</div>
          </div>
          <div class="punch-viewer-speakernotes-base" role="tabpanel">
            <div class="punch-viewer-speakernotes-text-header-container">
              <h3 class="punch-viewer-speakernotes-text-header">Slide 5 of 29</h3>
              <div class="punch-viewer-speakernotes-zoom-container">
                <div role="button" class="goog-inline-block jfk-button jfk-button-standard jfk-button-narrow jfk-button-collapse-right" tabindex="0" title="Zoom out" value="undefined" style="user-select: none;">
                  <div class="punch-viewer-speakernotes-zoom-minus punch-viewer-speakernotes-zoom-button jfk-button-img punch-viewer-icon-large"></div>
                </div>
                <div role="button" class="goog-inline-block jfk-button jfk-button-standard jfk-button-narrow jfk-button-collapse-left" tabindex="0" title="Zoom in" value="undefined" style="user-select: none;">
                  <div class="punch-viewer-speakernotes-zoom-plus punch-viewer-speakernotes-zoom-button jfk-button-img punch-viewer-icon-large"></div>
                </div>
              </div>
            </div>
            <div class="punch-viewer-speakernotes-text-body-scrollable" style="left: 331.885px;">
              <div class="punch-viewer-speakernotes-text-body">
                <div class="punch-viewer-speakernotes-text-body-zoomable">
                  <p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt;"><span style="font-size:11pt;font-family:Arial;color:#000000;background-color:transparent;font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre;white-space:pre-wrap;">Speaker notes </span>
                    <span style="font-size:10pt;font-family:Arial;color:#000000;background-color:transparent;font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre;white-space:pre-wrap;">[Slide 00:00:50][Chapter 00:01:00][Presentation 00:02:45]</span>
                  </p><br>
                </div>
              </div>
            </div>
          </div>
          <div style="display: none; left: 331.885px;" class="punch-viewer-speaker-qanda-content">
            <div class="punch-viewer-speaker-series-intro-container punch-viewer-speaker-series-intro-onboard-step2" tabindex="-1" role="tabpanel">
              <div class="punch-viewer-speaker-series-intro-onboard-container">
                <div class="punch-viewer-speaker-series-intro-onboard-card punch-viewer-speaker-series-intro-onboard-card0" aria-hidden="true">
                  <div class="punch-viewer-speaker-series-intro-image"><img alt="" src="//ssl.gstatic.com/docs/presentations/images/qanda_onboard_1_v2.png"></div>
                  <div class="punch-viewer-speaker-series-intro-header">Audience Q&amp;A</div>
                </div>
                <div class="punch-viewer-speaker-series-intro-onboard-card punch-viewer-speaker-series-intro-onboard-card1" aria-hidden="true">
                  <div class="punch-viewer-speaker-series-intro-image"><img alt="" src="//ssl.gstatic.com/docs/presentations/images/qanda_onboard_2_v2.png"></div>
                  <div class="punch-viewer-speaker-series-intro-header">Just click to present</div>
                </div>
                <div class="punch-viewer-speaker-series-intro-onboard-card punch-viewer-speaker-series-intro-onboard-card2" aria-hidden="false">
                  <div class="punch-viewer-speaker-series-intro-image"><img alt="" src="//ssl.gstatic.com/docs/presentations/images/qanda_onboard_3_v2.png"></div>
                  <div class="punch-viewer-speaker-series-intro-header">Answer all the right questions</div>
                </div>
              </div>
              <div class="punch-viewer-speaker-series-intro-buttons">
                <div role="button" class="goog-inline-block jfk-button jfk-button-standard" aria-hidden="true" style="user-select: none; display: none;">Continue recent</div>
                <div role="button" class="goog-inline-block jfk-button jfk-button-standard" tabindex="0" value="undefined" style="user-select: none;">Start new</div>
              </div>
            </div>
            <div class="punch-viewer-speaker-series-list-container" tabindex="-1" role="tabpanel" style="display: none;">
              <div class="punch-viewer-speaker-series-list-header">
                <div class="punch-viewer-speaker-series-list-exit goog-flat-button goog-inline-block" aria-label="Back" role="button" tabindex="0">
                  <div class="goog-flat-button-outer-box goog-inline-block">
                    <div class="goog-flat-button-inner-box goog-inline-block">
                      <div class="docs-icon goog-inline-block ">
                        <div class="docs-icon-img-container docs-icon-img docs-icon-arrow-back-dark" aria-hidden="true">&nbsp;</div>
                      </div>
                    </div>
                  </div>
                </div>Choose a session
              </div>
              <div class="punch-viewer-speaker-series-list"></div>
            </div>
            <div class="punch-viewer-speaker-series-container" tabindex="-1" role="tabpanel" style="display: none;">
              <h1 class="punch-viewer-speaker-series">
                <div aria-live="polite" role="status">
                  <div class="punch-viewer-speaker-series-status"></div>
                  <div class="punch-viewer-speaker-series-domain">
                    <div class="goog-inline-block goog-flat-menu-button jfk-select" role="listbox" aria-expanded="false" tabindex="0" aria-haspopup="false" aria-activedescendant=":38" style="user-select: none;">
                      <div class="goog-inline-block goog-flat-menu-button-caption" id=":38" role="option" aria-selected="true">Select an audience</div>
                      <div class="goog-inline-block goog-flat-menu-button-dropdown" aria-hidden="true">&nbsp;</div>
                    </div>
                  </div>
                </div>
                <div class="punch-viewer-speaker-series-domain-notice">Includes whitelisted domains</div>
                <div class="punch-viewer-speaker-series-checkbox">
                  <div class="jfk-slideToggle goog-inline-block" role="button" aria-disabled="true" aria-pressed="false" style="user-select: none;">
                    <div class="jfk-slideToggle-on">on</div>
                    <div class="jfk-slideToggle-off">off</div>
                    <div class="jfk-slideToggle-thumb"></div>
                  </div>
                </div>
                <div class="punch-viewer-speaker-series-url"></div>
              </h1>
              <div class="punch-viewer-speaker-questions" style="display: none"></div>
              <div class="punch-viewer-speaker-empty-questions">
                <div class="punch-viewer-speaker-empty-questions-image"><img alt="" src="//ssl.gstatic.com/docs/presentations/images/qanda_empty_v2.png"></div>
                <div class="punch-viewer-speaker-empty-questions-header">Questions appear here</div>
              </div>
              <div class="punch-viewer-speaker-questions-a11y docs-offscreen-z-index" aria-live="polite" role="status"></div>
            </div>
            <div class="docs-ui-toast" role="complementary" tabindex="0" aria-describedby=":27.d-u-t-c" style="display: none;">
              <div class="docs-ui-toast-content" id=":27.d-u-t-c">New top questions</div>
              <div class="docs-ui-toast-control-bar" id=":27.d-u-t-cb">
                <div class="docs-ui-toast-control punch-qanda-toast-action-label" role="button" tabindex="0" id="punch-qanda-toast-show">Show</div>
              </div>
            </div>
            <div class="punch-viewer-speaker-qanda-not-available" style="display: none;">
              <div class="punch-viewer-speaker-qanda-not-available-title">You need permission</div>
              <div class="punch-viewer-speaker-qanda-not-available-text">You can only view this presentation. To accept audience questions, ask the owner for comment or edit access.</div>
            </div>
          </div>
        </td>
      </tr>
    </tbody>
  </table>
  <div class="punch-viewer-speakernotes-dragger" style="left: 326px;">
    <div class="punch-viewer-speakernotes-dragger-icon"></div>
  </div>
</div>