如何在javascript中给出一个按钮列表的独立id？

<ul id="buttonList">
  <li><button id="button1">按钮1</button></li>
  <li><button id="button2">按钮2</button></li>
  <li><button id="button3">按钮3</button></li>
</ul>

var button1 = document.getElementById("button1");
var button2 = document.getElementById("button2");
var button3 = document.getElementById("button3");

button1.addEventListener("click", function() {
  // 点击按钮1时执行的代码
});

button2.style.backgroundColor = "red"; // 修改按钮2的背景颜色为红色