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

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

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

property style 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>
    <div id="box">Hello world</div>

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

if (box != null) {
  // ⛔️ Property 'style' does not exist on type 'Element'.ts(2339)
  box.style.backgroundColor = 'salmon';
}

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

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

src/index.ts

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const box = document.querySelector('#box') as HTMLElement | null;

if (box != null) {
  box.style.backgroundColor = 'salmon';
}

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

index.ts

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// 👇️ with getElementsByClassName
// type as HTMLCollectionOf<HTMLElement>
const boxes = document.getElementsByClassName(
  'box',
) as HTMLCollectionOf<HTMLElement>;

for (let i = 0; i < boxes.length; i++) {
  boxes[i].style.backgroundColor = 'salmon';
}

We could have also used the more specific HTMLDivElement type because we are typing a div element.

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 box variable stores anHTMLElement 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 box variable doesn't store a null value before accessing its style property.

src/index.ts

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// 👇️ const box: Element | null
const box = document.querySelector('#box') as HTMLElement | null;

// 👉️ box has type Element or null here

if (box != null) {
  // 👉️ box has type Element here
  box.style.backgroundColor = 'salmon';
}

TypeScript knows that the box variable has a type of HTMLElement in the if block and allows us to directly access its style 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 'style' does not exist on type 'Element' in TS

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

Conclusion #

Borislav Hadzhiev