实现右键，一键复制工能

  <div>
    <span id="copyMy" onmousedown="copyFn(event)" oncontextmenu="doNothing()">右键复制</span>
  </div>

<script>
  function doNothing() {  // 取消右键弹出的菜单
    window.event.returnValue = false;
    return false;
  }

  function copyFn(event) {
    var val = document.getElementById('copyMy');
    if (event.button === 2) { // 判断是否是鼠标右键
      window.getSelection().selectAllChildren(val);
      document.execCommand("Copy");
      alert("已复制好，可贴粘。");
    }
  }
</script>