Solving the Property 'scrollTop' does not exist on type 'EventTarget' Error in Angular

Learn how to correctly retrieve the scroll position in your Angular application without facing TypeScript errors related to `scrollTop`.
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Understanding the scrollTop TypeScript Error in Angular

When working with scroll events in Angular, you might encounter a common TypeScript error: Property 'scrollTop' does not exist on type 'EventTarget'. This can be frustrating, especially when you're trying to access important scroll metrics like the vertical position of the scroll bar. In this post, we will explore the cause of this error and provide a straightforward solution to help you retrieve the scrollTop value without any hassle.

The Problem

As you scroll through an element, you may want to track how far you've scrolled. For instance, you might have the following code snippet that adds an event listener to an element:

[[See Video to Reveal this Text or Code Snippet]]

While this code successfully logs the details of the scroll event to the console, you might notice that when you try to capture the scrollTop value using:

[[See Video to Reveal this Text or Code Snippet]]

You'll receive an error message stating: TS2339: Property 'scrollTop' does not exist on type 'EventTarget'. This happens because TypeScript doesn't know that the target property specifically refers to an HTMLElement that has a scrollTop property.

Why This Error Occurs

Solution: Using Type Assertions

Step 1: Update Your Code

Modify your scroll event listener like this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

Conclusion

By using type assertion, you can overcome the Property 'scrollTop' does not exist on type 'EventTarget' error and effectively retrieve the scrollTop value in your Angular applications. This method enhances your ability to work with scroll events without running into TypeScript complications, enabling you to build more dynamic and responsive user interfaces.

Happy coding, and may your scroll tracking be seamless!