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 because 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.

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

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

Borislav Hadzhiev