只是一个简单的实例，希望对大家编程有用。
HTML表单：
<form action="action.asp" method="post" name="myform">
Name and Surname: <br/>
<input type="text" name="nameandsurname" size="30"> <br/>
Email: <br/>
<input type="text" name="email" size="30"> <br/>
Age: <br/>
<input type="text" name="age" size="3"> <br/>
Gender: <br/>
<select size="1" name="gender">
<option>- Select gender -</option>
<option value="Male">Male</option>
<option value="Female">Female</option>
</select> <br/>
<input type="submit" value="Submit" onClick="check();return false;">
</form>
其中Check()函数是用来检测表单内容的。
JavaScript函数：
<SCRIPT LANGUAGE="JavaScript" TYPE="text/javascript">
function check() {
var nameandsurname = document.myform.nameandsurname;
var email = document.myform.email;
var age = document.myform.age;
var gender = document.myform.gender;
if ( nameandsurname.value.indexOf(" ") == -1) {
alert("Enter your Name and Surname.");
nameandsurname.focus();
} else if ((email.value.indexOf("@") == -1) || (email.value.indexOf(".") == -1)) {
alert("Enter your valid email address.");
email.focus();
} else if (! (parseInt(age.value) > 0)) {
alert("Enter your Age.");
age.focus();
} else if (gender.selectedIndex == 0) {
alert("Select your gender.");
gender.focus();
} else {
document.myform.submit();
}
}
</SCRIPT>
把上面的javascript代码放到你的网页的<head> </head>之间就可以了！
