Category: JavaScript Answers

Sometimes, we want to find the first scrollable parent element with JavaScript.

In this article, we’ll look at how to find the first scrollable parent element with JavaScript.

Find the First Scrollable Parent Element with JavaScript

To find the first scrollable parent element with JavaScript, we can recursively search for the parent that has scrollHeight bigger than clientHeight .

For instance, we can write the following HTML:

<div class="outer">
  <div class="inner">
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed dapibus aliquam iaculis. Pellentesque interdum elit sapien, quis interdum enim laoreet sed. Mauris varius magna ac dapibus molestie. Sed porttitor sapien eget ipsum aliquet, lacinia venenatis lacus finibus. Phasellus in nibh mauris. Interdum et malesuada fames ac ante ipsum primis in faucibus. Sed placerat tristique augue, id lacinia massa iaculis eu. Donec sed vestibulum odio. Fusce sit amet congue odio, eu consequat neque. Sed sed mauris id sem malesuada blandit eu at quam.
    <div class="content">
      <span id='start'>Scroll me into view</span>
    </div>
  </div>
</div>

Then we write:

const getScrollParent = (node) => {
  if (node === null) {
    return null;
  }

  if (node.scrollHeight > node.clientHeight) {
    return node;
  } else {
    return getScrollParent(node.parentNode);
  }
}

const span = document.querySelector('span')
const scrollable = getScrollParent(span)
console.log(scrollable)

to add the getScrollParent function that takes the HTML DOM node .

Then it checks if node.scrollHeight is bigger than node.clientHeight if the node isn’t null .

If it is, then it’s returned.

Otherwise, it calls getScrollParent with the node.parentNode to check the node up the DOM tree.

Then we call the function by getting the span with document.querySelector .

And then we call getScrollParent with it.

Therefore, we see that scrollable is the html element.

Conclusion

To find the first scrollable parent element with JavaScript, we can recursively search for the parent that has scrollHeight bigger than clientHeight .

Sometimes, we want to properly unload or destroy an HTML element with JavaScript.

In this article, we’ll look at how to properly unload or destroy an HTML element with JavaScript.

Properly Unload or Destroy an HTML Element with JavaScript

To properly unload or destroy an HTML element with JavaScript, we can pause the video, then remove the src attribute from the video element, and then call load again to reload the video element.

For instance, if we have the following HTML video element:

<video src='https://file-examples-com.github.io/uploads/2017/04/file_example_MP4_480_1_5MG.mp4' controls></video>

We can write:

const videoElement = document.querySelector('video');
videoElement.pause();
videoElement.removeAttribute('src');
videoElement.load();

to get the video element with document.querySelector .

Then we call pause to pause the video.

Next, we call removeAttribute with 'src' to remove the src attribute.

And then we call load to reload the video element.

Conclusion

To properly unload or destroy an HTML element with JavaScript, we can pause the video, then remove the src attribute from the video element, and then call load again to reload the video element.

Sometimes, we want to disable related videos with the Youtube JavaScript API. In this article, we’ll look at how to disable related videos with the Youtube JavaScript API.

Disable Related Videos with the Youtube JavaScript API

To disable related videos with the Youtube JavaScript API, we can set the rel property in the playerVars property to 0.

For instance, we can add the following HTML element for the video player:

<div id="player"></div>

Then we can write:

const tag = document.createElement("script");
tag.id = "iframe-demo";
tag.src = "https://www.youtube.com/iframe_api";
const [firstScriptTag] = document.getElementsByTagName("script");
firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

window.onYouTubeIframeAPIReady = () => {  
  const player = new window.YT.Player("player", {    
    width: 200,    
    height: 100,    
    videoId: "M7lc1UVf-VE",    
    playerVars: {      
      rel: 0,      
      showinfo: 0,      
      ecver: 2   
    }  
  });
};

to add the YouTube script tag with:

const tag = document.createElement("script");
tag.id = "iframe-demo";
tag.src = "https://www.youtube.com/iframe_api";
const [firstScriptTag] = document.getElementsByTagName("script");
firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

Then we set the window.onYouTubeIframeAPIReady to a function that invokes the window.YT.Player constructor with the ID of the element for the player as the first argument.

The 2nd argument is an object with various options like the video width and height and video ID. The playerVars.rel property is set to 0 so that related videos will not be shown.

Conclusion

To disable related videos with the Youtube JavaScript API, we can set the rel property in the playerVars property to 0.

Sometimes, we want to pass additional data via custom events in JavaScript.

In this article, we’ll look at how to pass additional data via custom events in JavaScript.

Pass Additional Data via Custom Events in JavaScript

To pass additional data via custom events in JavaScript, we can pass an object into the CustomEvent constructor.

For instance, we can write:

window.addEventListener("MyEvent", (evt) => {
  console.log(evt.detail);
});

const evt = new CustomEvent("MyEvent", {
  detail: "Any Object Here"
});
window.dispatchEvent(evt);

to listen to the MyEvent event with the window.addEventListener method.

In the event handler, we log the value of the evt.detail property, which will be set when we pass in an object into the CustomEvent constructor’s 2nd argument with the detail property.

The first argument of the CustomEvent constructor is the event name.

Finally, we call window.dispatchEvent with the evt object to emit the event.

Therefore, we should see 'Any Object Here' logged from the event handler.

Conclusion

To pass additional data via custom events in JavaScript, we can pass an object into the CustomEvent constructor.