新手求教

[chjian92]

大家好，小弟昨天刚开始学习javascript。明明是按照书上的例子打的，但是第二部分就是出不来。

<html>
<head>
<title>iRock</title>
<script type="text/javascript">
function touchrock(){
var userName=prompt("what is your name?","enter your name here.");
if(userName){
alert("it is good to meet you,"+username+".");
document.getElementById("rockImg").src="smile.png"
}
}
</script>
</head>
<body onload="alert(*Helloo,I am your pet rock.*);">
<div style="margin-top:100px;text-align:center">
<img id="rockImg" src="rock.png" alt="iRock" style="cursor:pointer" onclick="touchrock();"/>
</div>
</body>
</html>

代码就是上面这些，不知道哪里出差错了，希望大家帮帮忙，谢谢了

[似梦飞花]

<html>
<head>
<title>iRock</title>
<script type="text/javascript">
function touchrock(){
var userName=prompt("what is your name?","enter your name here.");
if(userName){
alert("it is good to meet you,"+username+".");
document.getElementById("rockImg").src="smile.png"
}
}
</script>
</head>
<body onload="alert('*Helloo,I am your pet rock.*');">
<div style="margin-top:100px;text-align:center">
<img id="rockImg" src="rock.png" alt="iRock" style="cursor:pointer" onclick="touchrock();"/>
</div>
</body>
</html>