如何在滚动div中将文本区域固定到屏幕底部

<div id="scrollingDiv">
  <div id="textArea">文本内容</div>
</div>

#scrollingDiv {
  height: 300px;
  overflow: auto;
}

#textArea {
  position: relative;
  /* 其他样式设置 */
}

var scrollingDiv = document.getElementById("scrollingDiv");
var textArea = document.getElementById("textArea");

scrollingDiv.addEventListener("scroll", function() {
  if (scrollingDiv.scrollTop + scrollingDiv.clientHeight >= scrollingDiv.scrollHeight) {
    textArea.style.position = "fixed";
    textArea.style.bottom = "0";
  } else {
    textArea.style.position = "relative";
    textArea.style.bottom = "auto";
  }
});