如何在单击按钮时显示工具提示

<button id="myButton" data-tooltip="这是工具提示的内容">点击我</button>

#tooltip {
  position: absolute;
  visibility: hidden;
  background-color: #000;
  color: #fff;
  padding: 5px;
  border-radius: 5px;
}

document.getElementById("myButton").addEventListener("click", function(event) {
  var tooltip = document.createElement("div");
  tooltip.id = "tooltip";
  tooltip.innerHTML = event.target.getAttribute("data-tooltip");
  
  var buttonRect = event.target.getBoundingClientRect();
  tooltip.style.top = buttonRect.top + buttonRect.height + "px";
  tooltip.style.left = buttonRect.left + "px";
  
  document.body.appendChild(tooltip);
});