Method insertBefore

packages/react-aria/src/collections/Document.ts:154–183

(newNode: ElementNode<T>, referenceNode: ElementNode<T>)

  }

  insertBefore(newNode: ElementNode<T>, referenceNode: ElementNode<T>): void {
    if (referenceNode == null) {
      return this.appendChild(newNode);
    }

    if (newNode.parentNode) {
      newNode.parentNode.removeChild(newNode);
    }

    newNode.nextSibling = referenceNode;
    newNode.previousSibling = referenceNode.previousSibling;
    // Ensure that the newNode's index is less than that of the reference node so that
    // invalidateChildIndices will properly use the newNode as the _minInvalidChildIndex, thus making sure
    // we will properly update the indexes of all sibiling nodes after the newNode. The value here doesn't matter
    // since updateChildIndices should calculate the proper indexes.
    newNode.index = referenceNode.index - 1;
    if (this.firstChild === referenceNode) {
      this.firstChild = newNode;
    } else if (referenceNode.previousSibling) {
      referenceNode.previousSibling.nextSibling = newNode;
    }

    referenceNode.previousSibling = newNode;
    newNode.parentNode = referenceNode.parentNode;

    this.invalidateChildIndices(newNode);
    if (this.isConnected) {
      this.ownerDocument.queueUpdate();
    }
  }

  removeChild(child: ElementNode<T>): void {
    if (child.parentNode !== this) {