                        课程
                    
                        /前端开发
                        
                            /JavaScript
                        
                        /JavaScript进阶篇

没反应？？？？

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>string对象 </title>
</head>
<body>
    <script type="text/javascript">
        var mystr="Hello World!";
        document.write("mystr");
        document.write(mystr.indexOf("o")+1);
        document.write(mystr.indexOf("o",mystr.indexOf("o")+1);
    </script>
</body>
</html>