如何将工具提示添加到锚定窗格中的按钮？

<button id="myButton">按钮</button>

var button = document.getElementById("myButton");
button.addEventListener("mouseover", showTooltip);

function showTooltip() {
  var tooltip = document.createElement("div");
  tooltip.innerHTML = "这是一个工具提示";
  tooltip.style.position = "absolute";
  tooltip.style.top = button.offsetTop + button.offsetHeight + "px";
  tooltip.style.left = button.offsetLeft + "px";
  tooltip.style.backgroundColor = "lightgray";
  tooltip.style.padding = "5px";
  tooltip.style.borderRadius = "5px";
  button.parentNode.insertBefore(tooltip, button.nextSibling);
}

button.addEventListener("mouseout", hideTooltip);

function hideTooltip() {
  var tooltip = button.nextSibling;
  tooltip.parentNode.removeChild(tooltip);
}