Property 'play' does not exist on type 'HTMLElement' in TS

Property 'play' does not exist on type 'HTMLElement' in TS #

The error "Property 'play' does not exist on type 'HTMLElement'" occurs when we try to call the play() method on an element that has a type of HTMLElement. To solve the error, use a type assertion to type the element as HTMLVideoElement before calling play.

property play not exist type htmlelement

This is the index.html file for the examples in this article.

index.html

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<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
  </head>
  <body>
    <video id="video" controls width="250">
      <source src="/media/cc0-videos/flower.webm" type="video/webm" />

      <source src="/media/cc0-videos/flower.mp4" type="video/mp4" />

      Sorry, your browser doesn't support embedded videos.
    </video>

    <script src="./src/index.ts"></script>
  </body>
</html>

And here is an example of how the error occurs in the index.ts file.

src/index.ts

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// 👇️ const video: HTMLElement | null
const video = document.getElementById('video');

if (video != null) {
  // ⛔️ Property 'play' does not exist on type 'HTMLElement'.ts(2339)
  video.play();
}

The reason we got the error is that the return type of the document.getElementById method is HTMLElement | null and the play method doesn't exist on the HTMLElement type.

To solve the error, use a type assertion to type the element as an HTMLVideoElement.

src/index.ts

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const video = document.getElementById('video') as HTMLVideoElement | null;

if (video != null) {
  video.play();
}

Type assertions are used when we have information about the type of a value that TypeScript can't know about.

We effectively tell TypeScript that the video variable stores anHTMLVideoElement or a null value and not to worry about it.

We used a union type to specify that the variable could still be null, because if an HTML element with the provided id does not exist in the DOM, the getElementById() method returns a null value.

We used a simple if statement that serves as a type guard to make sure the video variable doesn't store a null value before calling its play() method.

src/index.ts

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const video = document.getElementById('video') as HTMLVideoElement | null;

// 👉️ video has type HTMLVideoElement or null here

if (video != null) {
  // 👉️ video has type HTMLVideoElement here
  video.play();
}

TypeScript knows that the video variable has a type of HTMLVideoElement in the if block and allows us to directly call its play() method.

It's always a best practice to include null in the type assertion because the getElementById method would return null if no element with the provided id was found.

You might also use the optional chaining (?.) operator to short-circuit if the reference is equal to null or undefined

src/index.ts

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const video = document.getElementById('video') as HTMLVideoElement | null;

// 👇️ using optional chaining
video?.play();

The optional chaining operator short-circuits returning undefined if the reference is equal to null or undefined.

In other words, if the video variable stores a null value, we won't attempt to call the play() method on null and get a runtime error.

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Property 'play' does not exist on type 'HTMLElement' in TS

Property 'play' does not exist on type 'HTMLElement' in TS #

Conclusion #

Borislav Hadzhiev