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VirtualRepeatAngular

Synchronous / Asynchronous / Reactive Virtual Repeat implementation for Angular 2+. Supports variable height rows.

Install

npm i virtual-repeat-angular

Usage

Synchronous

<gc-virtual-repeat-container rowHeight="auto">
    <list-item-example *virtualRepeat="let row of collection; let i = index" [item]="row" [index]="i">
    </list-item-example>
</gc-virtual-repeat-container>

Where collection is an Array.

Asynchronous

<gc-virtual-repeat-container rowHeight="auto">
    <list-item-example *virtualRepeatAsynch="let row of asynchCollection; let i = index" [item]="row" [index]="i">
    </list-item-example>
</gc-virtual-repeat-container>

Where asynchCollection object must implement:

interface IAsynchCollection<T> {
    getLength(): Promise<number>;
    getItem(i: number): Promise<T>;
}

Reactive

<gc-virtual-repeat-container rowHeight="auto">
    <list-item-example *virtualRepeatReactive="let row of reactiveCollection; let i = index" [item]="row" [index]="i">
    </list-item-example>
</gc-virtual-repeat-container>

Where reactiveCollection object must implement:

export interface IReactiveCollection<T> {
  length$: Observable<number>;
  items$: Observable<{ index: number; item: T }>;
  reset$: Observable<boolean>;

  connect(): void;
  disconnect(): void;

  reset(): void;

  requestLength(): void;
  requestItem(index: number): void;
}

For each call to requestLength() the observable length$ must emit the collection's length.

For each call to requestItem() the observable requestItem$ must emit the collection's item at the index position (zero based).

For each call to reset() the collection must clean its internal state and the observable reset$ must emit some boolean (its value is not used). The virtual repeat library will request the data again.

This method must be called by the library's client when the data set to show has changed, because of a sort / filter operation on it, or because it's known that an item has been added or deleted.

The connect / disconnect methods will be called by the virtual repeat library.

Parameters

  • rowHeight [number|'auto']: item's row height in pixels. With auto-height (rowHeight="auto") the height of all rows is computed as the mean height of the first rendered page, if the height is fixed. Otherwise, if the height of each cell is variable, the mean height is updated for each row and the scroll size and position adjusted to it.

Notes

  • <gc-virtual-repeat-container> must be inserted inside an element with display: flex & flex: 1 to perform properly.
  • Inside the container you can place any kind of HTML element that is full row, as shown in the demo using table's <tr>.

Demo

See https://gerardcarbo.github.io/virtual-repeat-angular/

License

MIT

Releases

GitHub Releases Page

Acknowledgements

Derived from previous work of Bob Yuan but using an offsetter div instead of absolute item positioning. Revamped also to support asynch and reactive collections, and variable height rows.