Category: JavaScript Answers

Sometimes, we want to play audio with JavaScript.

In this article, we’ll look at how to play audio with JavaScript.

How to play audio with JavaScript?

To play audio with JavaScript, we call the play method.

For instance, we write

const audio = new Audio("audio_file.mp3");
audio.play();

to create an audio element with the Audio constructor called with the path to the audio file.

Then we call play to play the audio file.

Conclusion

To play audio with JavaScript, we call the play method.

Sometimes, we want to prevent users from submitting a form by hitting Enter with JavaScript.

In this article, we’ll look at how to prevent users from submitting a form by hitting Enter with JavaScript.

How to prevent users from submitting a form by hitting Enter with JavaScript?

To prevent users from submitting a form by hitting Enter with JavaScript, we can check the keyCode and keyIdentifier properties.

For instance, we write

window.addEventListener(
  "keydown",
  (e) => {
    if (
      e.keyIdentifier === "U+000A" ||
      e.keyIdentifier === "Enter" ||
      e.keyCode === 13
    ) {
      e.preventDefault();
      return false;
    }
  },
  true
);

to listen to the keydown event on the page with addEventListener.

In the keydown listener function, we check for the enter key press with

e.keyIdentifier === "U+000A" || e.keyIdentifier === "Enter" || e.keyCode === 13

If any of them is true, then we call preventDefault to stop the submission.

Conclusion

To prevent users from submitting a form by hitting Enter with JavaScript, we can check the keyCode and keyIdentifier properties.

Sometimes, we want to make JavaScript execute after page load.

In this article, we’ll look at how to make JavaScript execute after page load.

How to make JavaScript execute after page load?

To make JavaScript execute after page load, we set window.onload to a function that’s called after the page is loaded.

For instance, we write

window.onload = () => {
  //...
};

to set window.onload to a function that’s called when the page is done loading.

The code inside the function will run after the page finishes loading.

Conclusion

To make JavaScript execute after page load, we set window.onload to a function that’s called after the page is loaded.

Sometimes, we want to tell if a DOM element is visible in the current viewport with JavaScript.

In this article, we’ll look at how to tell if a DOM element is visible in the current viewport with JavaScript.

How to tell if a DOM element is visible in the current viewport with JavaScript?

To tell if a DOM element is visible in the current viewport with JavaScript, we use the intersection observer.

For instance, we write

const el = document.querySelector("#el");
const observer = new window.IntersectionObserver(
  ([entry]) => {
    if (entry.isIntersecting) {
      console.log("ENTER");
      return;
    }
    console.log("LEAVE");
  },
  {
    root: null,
    threshold: 0.1,
  }
);

observer.observe(el);

to create an IntersectionObserver object with a callback and an object.

The callback is run wwhen the element we’re oberving enters or leaves the container.

We can check if it’s intersecting with the container with isIntersecting.

The object has the root property that specifies the container to watch for intersection for.

threshold has the threshold of the intersection before the callback is run.

Conclusion

To tell if a DOM element is visible in the current viewport with JavaScript, we use the intersection observer.

Sometimes, we want to move an element into another element with JavaScript.

In this article, we’ll look at how to move an element into another element with JavaScript.

How to move an element into another element with JavaScript?

To move an element into another element with JavaScript, we can use a fragment.

For instance, we write

const fragment = document.createDocumentFragment();
fragment.appendChild(document.getElementById("source"));
document.getElementById("destination").appendChild(fragment);

to call createDocumentFragment to create a document fragment.

Then we call fragment.appendChild to append an element as the last child of the fragment.

Then we use

document.getElementById("destination").appendChild(fragment)

to append the fragment to the element with ID destination.

Conclusion

To move an element into another element with JavaScript, we can use a fragment.