我这段代码为什么文本打印不出来?
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>系好安全带,准备启航</title>
<script type="text/javascript">
document.write("文本");
function ocan(){
var mychar="文本1";
alert(mychar);
}
</script>
</head>
<body>
<form>
<input name="button" type="button" value="启航" onclick="ocan()" />
</form>
</body>
</html>