轉載w3school
這段腳本在達到文本框的最大長度時跳到下一個文本框
<html>
<head>
<script type="text/javascript">
function checkLen(x,y)
{
if (y.length==x.maxLength)
{
var next=x.tabIndex
if (next<document.getElementById("myForm").length)
{
document.getElementById("myForm").elements[next].focus()
}
}
}
</script>
</head>
<body>
<p>這段腳本在達到文本框的最大長度時跳到下一個文本框：</p>
<form id="myForm">
<input size="3" tabindex="1" maxlength="3" οnkeyup="checkLen(this,this.value)">
<input size="2" tabindex="2" maxlength="2" οnkeyup="checkLen(this,this.value)">
<input size="3" tabindex="3" maxlength="3" οnkeyup="checkLen(this,this.value)">
</form>
</body>
</html>