這樣怎么不行？
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Math </title>
<script type="text/javascript">
function dian(){
? ? var i =document.getElementById("txt1").value;
? ? var j =document.getElementById("txt2").value;
? ? ?j =Math.ceil(i);
? ? }
</script>
</head>
<body>
<form>
?<input type="txt" name="文本" value="輸入" id="txt1" /><br />
?<input type="button" name="按鈕" value="向上取整" onclick="dian()"/><br />
?<input type="txt" name="文本" value="結果" id="txt2"/>
</form>
</body>
</html>
2016-05-26
試試看
var i =parseInt(document.getElementById("txt1").value);
var ?j =Math.ceil(i);
document.getElementById("txt2").value=j;
2016-07-28
input 的屬性type="text"
2016-05-26
i和j要用parseInt()強制轉換