为什么只出现一个hello java
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
<script type="text/javascript">
window.onload=function(){
var myvar = document.getElementById("icon");
document.write(myvar.innerHTML);
myvar.innerHTML = "hello java";
document.write(myvar.innerHTML);}
</script>
</head>
<body>
<p id = "icon">
hello javascript
</p>
</body>
</html>
