JavaScript 实现自定义右键菜单的两种方法

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    body {
      height: 3000px;
    }
    
    .menu {
      width: 100px;
      height: 280px;
      background-color: red;
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }
  </style>
</head>

<body>
  <script>
    var Bon = true;
    var menu = null;
    document.oncontextmenu = function(event) {
      if (Bon) {
        menu = document.createElement("div");
        menu.classList.add("menu");
        document.body.appendChild(menu);
        menu.style.left = event.pageX + "px";
        menu.style.top = event.pageY + "px";
        menu.style.display = "block";
        Bon = false;
        event.preventDefault();
      } else {
        menu.style.left = event.pageX + "px";
        menu.style.top = event.pageY + "px";
        event.preventDefault();
      }
    }

    document.onmousedown = function(e) {
      if (e.button == 0) {
        var menu = document.querySelector(".menu");
        document.body.removeChild(menu);
        Bon = true;
      }
    }
  </script>
</body>

</html>

<div class="menu"></div>
 <script>
    var menu = document.querySelector(".menu");
    document.oncontextmenu = function(event) {
      menu.style.left = event.pageX + "px";
      menu.style.top = event.pageY + "px";
      menu.style.display = "block";
      event.preventDefault();
    }
    document.onmousedown = function(e) {
      if (e.button == 0) {
        menu.style.display = "none";
      }
    }
</script>