签出智能滚动。

如果滚动条位于底部，则随附文本，您将看到新文本。

If the scrollbar is at the bottom, then as text is appended you will see the new text.

如果用户滚动到其他位置，则视口将保持不变，直到用户滚动到底部。

If the user has scrolled to a different position, then the viewport will stay there until the user scrolls back to the bottom.