Property 'src' does not exist on type 'Element' in TS

Property 'src' does not exist on type 'Element' in TS #

The error "Property 'src' does not exist on type 'Element'" occurs when we try to access the src property on an element that has a type of Element. To solve the error, use a type assertion to type the element as HTMLImageElement before accessing the property.

property src not exist type element

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>
    <img id="photo" width="400" height="400" src="dog.jpg" />

    <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 image: Element | null
const image = document.querySelector('#photo');

if (image != null) {
  // ⛔️ Property 'src' does not exist on type 'Element'.ts(2339)
  image.src = 'photo.jpg';
}

The reason we got the error is that the return type of the document.querySelector method is Element | null and the src property doesn't exist on the Element type.

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

src/index.ts

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const image = document.querySelector('#photo') as HTMLImageElement | null;

if (image != null) {
  image.src = 'photo.jpg';
}

If you used the document.getElementsByClassName method, type the collection as HTMLCollectionOf<HTMLImageElement>.

src/index.ts

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// 👇️ with getElementsByClassName
// type as HTMLCollectionOf<HTMLImageElement>
const images = document.getElementsByClassName(
  'img',
) as HTMLCollectionOf<HTMLImageElement>;

for (let i = 0; i < images.length; i++) {
  images[i].src = 'photo.jpg';
}

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 image variable stores anHTMLImageElement 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 selector does not exist in the DOM, the querySelector() method returns a null value.

We used a simple if statement that serves as a type guard to make sure the image variable doesn't store a null value before accessing its src property.

src/index.ts

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const image = document.querySelector('#photo') as HTMLImageElement | null;

// 👉️ image has type HTMLImageElement or null here

if (image != null) {
  // 👉️ image has type HTMLImageElement here
  image.src = 'photo.jpg';
}

TypeScript knows that the image variable has a type of HTMLImageElement in the if block and allows us to directly access its src property.

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

Conclusion #

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Property 'src' does not exist on type 'Element' in TS

Property 'src' does not exist on type 'Element' in TS #

Conclusion #

Borislav Hadzhiev