求大神指导，为什么我打开网页之后，地址出错了，总是显示 http://www.imooc.com/code/http：//www.imooc.com/
<!DOCTYPE html>
<html>
<head>
<title> new document </title>
<meta http-equiv="Content-Type" content="text/html; charset=gbk"/>
<script type="text/javascript">
function openWindow()
{
var newWindow = confirm("是否打开新窗口");
if (newWindow==true)
{
var address = prompt ("通过输入对话框，确定打开的网址","http：//www.imooc.com/");
if (address!=null)
{
window.open(address, '_blank', 'width=400,height=500,menubar=no,toolbar=no');
}
else
{
alert("再见");
}
}
else
{
alert("再见");
}
}
</script>
</head>
<body>
<input type="button" value="新窗口打开网站" onclick="openWindow()" />
</body>
</html>
