function宣言の外にメソッドを記述すると、自動的に動いてしまうのがミソ



<html>

<head>
<meta http-equiv="Content-Type" content="text/html; charset=shift_jis">
<meta name="GENERATOR" content="Microsoft FrontPage 4.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
</head>


<body>
<p><input type="text" size="82" name="ppp"></p>
</body>

</html>

<script language="JavaScript">

var count=0;
var midasi = "ただ今印刷中でしゅ　";
var progre = "■";
var disp="";

alert("aaa");

ppp.value = count;


disp = midasi ;




intervalId = setInterval("putmsg()",500);


function putmsg(){
	
	if (count < 10 ){
		disp = disp  + progre ;
		count ++;
	}else{
		disp = midasi ;
		count =0;
	}

	ppp.value = disp ;

	
}

</script>