<html>
<head>
<script type="text/javascript">
function validate_required(field,alerttxt)
{
with (field)
{
if (value==null||value=="")
{alert(alerttxt);return false}
else {return true}
}
}
function validate_form(thisform)
{
with (thisform)
{
if (validate_required(email,"Email must be filled out!")==false)
{email.focus();return false}
}
}
</script>
</head>
<body>
<form action="submitpage.htm" onsubmit="return validate_form(this)" method="post">
Email: <input type="text" name="email" size="30">
<input type="submit" value="Submit">
</form>
</body>
</html>
补充：
with (object)
statements
例：
x = Math.cos(3 * Math.PI) + Math.sin(Math.LN10)
y = Math.tan(14 * Math.E)
当使用 with 语句时：
with (Math){
x = cos(3 * PI) + sin (LN10)
y = tan(14 * E)
}