jigScrollAmount publishes an element's scroll geometry as signals and fires endReached when the user scrolls near the bottom. It is the primitive behind "load more" lists and scroll-linked UI.

Reading Scroll State

The directive has no exportAs, so query it with viewChild to read its signals:

The exposed signals are listed under Properties in the API tab.

Geometry is resynced whenever the observed element resizes or the host's own content grows, so distanceFromEnd stays correct after rows are appended — no manual refresh call.

Infinite Scrolling

endReached is edge-triggered: it fires once as the scroll position crosses into the threshold zone and does not fire again until the position leaves the zone and comes back. Appending rows pushes the end away, which re-arms it.

jigScrollAmountEndThreshold is the distance in pixels at which it fires — 0 means "at the very bottom", a larger value prefetches earlier.

Still guard your loader against overlapping loads. Edge-triggering removes the repeated-fire problem, not the case where the user scrolls back and forth across the threshold while a request is in flight.

For a guarded consumer, read distanceFromEnd directly instead of listening to the output — you get the same information continuously, with no edge semantics to reason about.

External Scroll Container

When the scrolling element is not the host — a wrapper you don't control, or a scroller elsewhere in the page — point the directive at it:

<div #outer class="scroll-area">
  <ul jigScrollAmount [jigScrollAmountContainer]="outer" (endReached)="loadMore()">
    …
  </ul>
</div>

Scroll events and dimensions are then read from that element, while the host still contributes its own size to the resync.

Server-side Rendering

Scroll listeners and geometry sync run in afterRenderEffect, so nothing is observed on the server. The signals start at the element's initial values (0) and become live after the first client render.

Related

The Scroller control builds virtual scrolling on top of this idea, and the Table uses it for lazy infinite scroll. Reach for jigScrollAmount when you want the raw numbers instead.