JS 一键复制

   $(function(){
      $("#btn_code").click(function(){
        var code=$("#active_code").text();
        copyToClipboard(code);
     }); 
    });
  function copyToClipboard(maintext){
      if (window.clipboardData){
        window.clipboardData.setData("Text", maintext);
        }else if (window.netscape){
          try{
            netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
        }catch(e){
            alert("该浏览器不支持一键复制！\n请手工复制文本框链接地址～");
        }
        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=maintext;
        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);
      }
      alert("已经复制到剪贴板\n\n" + maintext);
    }