我在 html 中编写了以下代码,并且 javascript 文件也嵌入在下面
<!DOCTYPE html>
<meta charset="utf-8">
<HTML>
<head>
<link rel="stylesheet" href="admin.css"/>
<script type="text/javascript" src="common.js"></script>
</head>
<BODY>
<div class="adminnav" id="adminnav">
<ul>
<li><a href="#">Insert</a>
<ul>
<li><a href="addcourse.html">Insert Course</a></li>
<li><a href="addstudent.html">Insert Student</a></li>
<li><a href="addteacher.html">Insert Teacher</a></li>
<li><a href="addsubject.html">Insert Subject</a></li>
</ul>
</li>
</ul>
</div>
<div class="addcourse" >
<form name="course" onSubmit='return validcourse()' method="POST">
Course Name:
<input type="text" name="coursename" id="cname" /><br>
Duration:<input type="text" name="cd"/>
<br>
Course Id:<input name="cid" type="text" /><br>
<input type="submit" value="submit" name="submit"><input type="reset" name="coursereset">
</form>
</div>
</BODY>
</HTML>
common.js
function validcourse()
{
var course_name=document.course.coursename;
var course_duration=document.course.cd;
var course_id=document.course.cid;
if(course_name_valid(course_name))
{
{
if(course_duration_valid(course_duration))
{
if(course_id_valid(cid))
{
}
}
}
}
}
function course_name_valid(course_name)
{
var letters=/^[A-Za-z]+$/;
if(course_name.value.match(letters))
{
return true;
}
else
{
alert("Course name must have alphabets only");
course_name.focus();
return false;
}
}
function course_duration_valid(course_duration)
{
var letters=/^[1-9]+$/;
if(cd.value.match(letters))
{
return true;
}
else
{
alert("Course Duration can have numbers only");
course_duration.focus();
retun false;
}
}
function course_id_valid(course_id)
{
var letters=/^[0-9a-zA-z]+$/;
if(course_id.value.match(letters))
{
return true;
}
else
{
alert('Course ID must have character and numeric values only');
course_id.focus();
return false;
}
}
我的问题是什么都没有发生,没有给出错误消息。错误消息仅针对课程名称而不针对课程持续时间和课程 ID?
这是 jsfiddle http://jsfiddle.net/amolkarale/aTfq6/1/的链接