<div id="box" style="color:red;width: 100%;height:1000px;" >
 <div id="left" style="float:left;width:500px;margin-left: 50px;height:500px;background: #cdeddf;">
  
 </div> 
 <div id="right" style="float:right;width:600px;margin-right: 50px;height:500px;background: #cdeaae;">
 </div>
 <ul id="menu" style="position: absolute;visibility: hidden;list-style: none;">
  <li>按鈕1</li>
  <li>按鈕2</li>
  <li>按鈕3</li>
 </ul>
</div>

// 添加contextmenu事件
 var right = document.getElementById("right");
 EventUtil.addEventListener(right, "contextmenu", function(event) {
 event = EventUtil.getEvent(event);
 EventUtil.preventDefault(event);
 var menu = document.getElementById("menu");
 
 // 獲取鼠標右擊時的坐標，并設置上下文菜單出現(xiàn)位置
 page = EventUtil.getPagePosition(event); 
 menu.style.left = page.pageX + "px";
 menu.style.top = page.pageY + "px";
 menu.style.visibility = "visible";
 });
 
 // 添加隱藏上下文菜單事件
 EventUtil.addEventListener(document, "click", function(event) {
 var menu = document.getElementById("menu");
 menu.style.visibility = "hidden";
 });