setUInterval为啥没效果啊


<html>
    <head>  <!--
        <meta charset="Utf-8" />  -->
        <title>测试</title>
    </head>
    <body>
        <span>测试颜色</span>
    </body>

    <script type="text/javascript" > 
    
        setUInterval(function(){
            alert("两秒跳一次哦");
        },2000); 

    </script>
</html>

是setInterval