inView.ts

export function isElementInView(container: HTMLElement, element: HTMLElement, partial: boolean) {
  if (!container || !element) {
    return false;
  }
  const containerBounds = container.getBoundingClientRect();
  const elementBounds = element.getBoundingClientRect();
  const containerBoundsLeft = Math.floor(containerBounds.left);
  const containerBoundsRight = Math.floor(containerBounds.right);
  const elementBoundsLeft = Math.floor(elementBounds.left);
  const elementBoundsRight = Math.floor(elementBounds.right);

  // Check if in view
  const isTotallyInView = elementBoundsLeft >= containerBoundsLeft && elementBoundsRight <= containerBoundsRight;
  const isPartiallyInView =
    partial &&
    ((elementBoundsLeft < containerBoundsLeft && elementBoundsRight > containerBoundsLeft) ||
      (elementBoundsRight > containerBoundsRight && elementBoundsLeft < containerBoundsRight));

  // Return outcome
  return isTotallyInView || isPartiallyInView;
}