如何在单击时切换按钮颜色，并在再次单击时将颜色更改回以前的颜色

<button id="myButton" onclick="changeColor()">按钮</button>

function changeColor() {
  var button = document.getElementById("myButton");
  var currentColor = button.style.backgroundColor;
  var previousColor = button.getAttribute("data-previous-color");

  if (currentColor === previousColor) {
    // 切换颜色
    var newColor = getRandomColor();
    button.style.backgroundColor = newColor;
    button.setAttribute("data-previous-color", currentColor);
  } else {
    // 将颜色更改回以前的颜色
    button.style.backgroundColor = previousColor;
  }
}

function getRandomColor() {
  var letters = "0123456789ABCDEF";
  var color = "#";
  for (var i = 0; i < 6; i++) {
    color += letters[Math.floor(Math.random() * 16)];
  }
  return color;
}