function copy_clip() {     var url = $("#back_info").html();     //需要复制的内容     var txt = url.substring(url.indexOf(":") + 1, url.length);     if (window.clipboardData) {         window.clipboardData.clearData();         window.clipboardData.setData("Text", txt);         alert('恭喜，复制成功！');     } else if (navigator.userAgent.indexOf("Opera") != -1) {         window.location = txt;     } else if (window.netscape) {         try {             netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");         } catch (e) {             alert("您的firefox安全限制限制您进行剪贴板操作，请在新窗口的地址栏里输入'about:config'然后找到'signed.applets.codebase_principal_support'设置为true'");             return false;         }         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);     } }