判断窗口是关闭还是刷新 
<script> 
function window.onbeforeunload(){ 
with(window.event)if(clientY<0&&clientX>document.body.clientWidth||altKey)alert("关闭") 
} 
</script>

firefox 复制文本js代码

<script> 
function copyToClipboard(txt) { 
     if(window.clipboardData) { 
             window.clipboardData.clearData(); 
             window.clipboardData.setData("Text", txt); 
     } else if(navigator.userAgent.indexOf("Opera") != -1) { 
          window.location = txt; 
     } else if (window.netscape) { 
          try { 
               netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect"); 
          } catch (e) { 
               alert("被浏览器拒绝！\n请在浏览器地址栏输入'about:config'并回车\n然后将'signed.applets.codebase_principal_support'设置为'true'"); 
          } 
          var clip = Components.classes['@mozilla.org/widget/clipboard;1'].createInstance(Components.interfaces.nsIClipboard); 
          if (!clip) 
               return; 
          var trans = Components.classes['@mozilla.org/widget/transferable;1'].createInstance(Components.interfaces.nsITransferable); 
          if (!trans) 
               return; 
          trans.addDataFlavor('text/unicode'); 
          var str = new Object(); 
          var len = new Object(); 
          var str = Components.classes["@mozilla.org/supports-string;1"].createInstance(Components.interfaces.nsISupportsString); 
          var copytext = txt; 
          str.data = copytext; 
          trans.setTransferData("text/unicode",str,copytext.length*2); 
          var clipid = Components.interfaces.nsIClipboard; 
          if (!clip) 
               return false; 
          clip.setData(trans,null,clipid.kGlobalClipboard); 
     } 
} 
</script> 
<button onclick="copyToClipboard('你好！');">复制文本“你好！”</button> 
<textarea id="test"></textarea>