Function triggerIntersection

src/test-utils.ts:172–230

(
  elements: Element[],
  trigger: boolean | number,
  observer: IntersectionObserver,
  item: Item,
)

}

function triggerIntersection(
  elements: Element[],
  trigger: boolean | number,
  observer: IntersectionObserver,
  item: Item,
) {
  const entries: IntersectionObserverEntry[] = [];

  const isIntersecting =
    typeof trigger === "number"
      ? observer.thresholds.some((threshold) => trigger >= threshold)
      : trigger;

  let ratio: number;

  if (typeof trigger === "number") {
    const intersectedThresholds = observer.thresholds.filter(
      (threshold) => trigger >= threshold,
    );
    ratio =
      intersectedThresholds.length > 0
        ? intersectedThresholds[intersectedThresholds.length - 1]
        : 0;
  } else {
    ratio = trigger ? 1 : 0;
  }

  for (const element of elements) {
    entries.push(<IntersectionObserverEntry>{
      boundingClientRect: element.getBoundingClientRect(),
      intersectionRatio: ratio,
      intersectionRect: isIntersecting
        ? element.getBoundingClientRect()
        : {
            bottom: 0,
            height: 0,
            left: 0,
            right: 0,
            top: 0,
            width: 0,
            x: 0,
            y: 0,
            toJSON() {},
          },
      isIntersecting,
      rootBounds:
        observer.root instanceof Element
          ? observer.root?.getBoundingClientRect()
          : null,
      target: element,
      time: Date.now() - item.created,
    });
  }

  // Trigger the IntersectionObserver callback with all the entries
  const act = getActFn();
  if (act) act(() => item.callback(entries, observer));
  else item.callback(entries, observer);