Function findDeepOpenElement

src/patch-streaming-html.ts:152–177

Walk DOM to the innermost open element matching the track stack

(
  container: HTMLElement,
  stack: string[],
)

/** Walk DOM to the innermost open element matching the track stack */
function findDeepOpenElement(
  container: HTMLElement,
  stack: string[],
): HTMLElement | null {
  let node: Element = container;

  for (const tag of stack) {
    const tagLower = tag.toLowerCase();
    let matched: Element | null = null;

    for (let i = node.children.length - 1; i >= 0; i--) {
      const child = node.children[i]!;
      if (child.tagName.toLowerCase() === tagLower) {
        matched = child;
        break;
      }
    }

    if (!matched) {
      return null;
    }
    node = matched;
  }

  return node as HTMLElement;
}

/** Deepest last text node under `root` (matches insertAdjacentText tail). */
function findLastTextNode(root: Node): Text | null {