Скачать или смотреть Resolving Angular Material Virtual Scroll Jumps

Discover how to fix the issue of items jumping around in Angular Material Virtual Scroll with this informative guide on setting the correct item size.
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Resolving Angular Material Virtual Scroll Jumps: A Comprehensive Guide

When working with infinite scroll and virtual scrolling in Angular, developers often encounter a perplexing issue: the items in their Angular Material virtual scroll component start jumping around unpredictably. This behavior disrupts user experience and can lead to confusion. In this guide, we will explore a simple yet effective solution to this problem by ensuring the correct item size is defined for the virtual scroll viewport.

Understanding the Problem

You may have implemented a virtual scroll in your Angular application using Angular Material's cdk-virtual-scroll-viewport, which allows for efficient rendering of large lists by only displaying items in view. However, if you notice that the scroll position shifts unexpectedly, this can be frustrating.

Example Scenario

You have the following HTML structure for your virtual scroll:

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Upon scrolling, you receive jumpy results like the following:

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This inconsistency can lead to your view unexpectedly jumping toward the end of the list, disrupting the user's interaction.

Solution: Setting the Correct Item Size

The primary reason for this jumping behavior often lies in the discrepancies between the set item size and the actual height of the list items. The virtual scroll calculates its offsets based on the assumed height of each item, which is defined by the itemSize attribute.

Step-by-Step Resolution

Define the Item Size: Ensure that the itemSize prop of the cdk-virtual-scroll-viewport accurately reflects the height of each item in pixels.

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Maintain Consistency in CSS: It is essential that the item dimensions in your CSS match the defined item size. If your item is expected to be 42px in height, set the height in your CSS accordingly:

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Adjust Dynamically if Necessary: If your items have variable heights, consider implementing a mechanism to dynamically calculate and apply item sizes in order to maintain a smooth scrolling experience.

Example of Correct Setup

Here’s how the complete implementation should look once you've set the correct values:

HTML

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CSS

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Conclusion

By accurately setting the itemSize property and aligning it with your CSS styles, you can effectively eliminate the jumping behavior in Angular Material's virtual scrolling component. This small change can significantly enhance the user experience by providing smooth and predictable scrolling.

If you continue to experience difficulties, consider double-checking the heights and ensuring there are no other styles overriding your intended settings.

Happy Coding!

With these adjustments, you can now harness the power of Angular Material's virtual scrolling without the nuisance of unwanted jumps. Enjoy developing seamless and smooth experiences in your applications!