@rdlabo/ngx-cdk-scroll-strategies

Angular CDK virtual scroll with variable and dynamic item heights.

@rdlabo/ngx-cdk-scroll-strategies is an Angular CDK virtual scroll strategy for lists with variable item heights. It lets you supply the exact pixel size of every item instead of requiring one fixed [itemSize] for the whole list.

Use [itemDynamicSizes] with known or measured item heights. Unlike the experimental [autosize] strategy, this library does not estimate unmeasured items from an average size. It works with @angular/cdk/scrolling and does not depend on Ionic.

Installation

npm install @rdlabo/ngx-cdk-scroll-strategies

Then follow Simple Usage for a complete viewport with known heights.

Every data item must have one corresponding itemDynamicSizes entry in the same order. Each itemSize must be a finite number greater than zero. If Angular updates the data and size signals in separate turns, the strategy keeps the last complete geometry until their lengths match; it never estimates unknown heights.

When to use this strategy

Use this library when:

• list items or rows have different heights;
• dynamic item heights can be calculated from data or measured from rendered components;
• scrollToIndex and scroll positions must use exact variable-height geometry; or
• a chat UI needs reverse virtual scrolling.

If an item height is not known in advance, measure it and pass the result as shown in Advanced Usage. This is not a drop-in strategy that discovers every unknown DOM height automatically.

This library is based largely on Virtual scrolling of content with variable height with Angular.

Choose by scrolling goal

| Goal | Guide | | --- | --- | | Specify each item height | Simple Usage | | Measure item components | Advanced Usage | | Reverse chat-style scrolling | Reverse Scroll |

Full documentation: https://docs.rdlabo.dev/projects/ngx-cdk-scroll-strategies