拷贝文字到剪贴板firefox ie 通用js函数

1. function copyToClipboard(txt) {          
2.   
3.      if(window.clipboardData) {          
4.   
5.               window.clipboardData.clearData();          
6.   
7.               window.clipboardData.setData("Text", txt);          
8.   
9.       } else if(navigator.userAgent.indexOf("Opera") != -1) {          
10.   
11.            window.location = txt;          
12.   
13.       } else if (window.netscape) {          
14.   
15.           try {          
16.   
17.                 netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");          
18.   
19.            } catch (e) {          
20.   
21.                 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'");          
22.   
23.            }          
24.   
25.           var clip = Components.classes['@mozilla.org/widget/clipboard;1'].createInstance(Components.interfaces.nsIClipboard);          
26.   
27.           if (!clip)          
28.   
29.                return;          
30.   
31.           var trans = Components.classes['@mozilla.org/widget/transferable;1'].createInstance(Components.interfaces.nsITransferable);          
32.   
33.           if (!trans)          
34.   
35.                return;          
36.   
37.            trans.addDataFlavor('text/unicode');          
38.   
39.           var str = new Object();          
40.   
41.           var len = new Object();          
42.   
43.           var str = Components.classes["@mozilla.org/supports-string;1"].createInstance(Components.interfaces.nsISupportsString);          
44.   
45.           var copytext = txt;          
46.   
47.            str.data = copytext;          
48.   
49.            trans.setTransferData("text/unicode",str,copytext.length*2);          
50.   
51.           var clipid = Components.interfaces.nsIClipboard;          
52.   
53.           if (!clip)          
54.   
55.                return false;          
56.   
57.            clip.setData(trans,null,clipid.kGlobalClipboard);          
58.   
59.            alert("复制成功！")          
60.   
61.       }          
62.   
63. }