剪切板，真实可用，兼容IE跟FF

function saveToClipboard(txt) {      
	if(window.clipboardData) {      
		window.clipboardData.clearData();      
		window.clipboardData.setData("Text", txt);     
		alert("已经复制到剪切板！")    
	} else if(navigator.userAgent.indexOf("Opera") != -1) {      
		window.location = txt;      
		alert("已经复制到剪切板！");   
	} 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);      
		alert("已经复制到剪切板！")      
	}
}