javascript and jsp
when i try to access a jsp variable in javascript i always get it as null. why is this so? how do i get actual jsp variable value in javascript. here is my code
<%! String oldpassword; %>
<html>
<head>
<script type="text/javascript">
function redirect()
{
var oldpassword_actual="<%= oldpassword %>";
var oldpassword_entered=document.form.oldpassword.value;
var newpassword=document.form.newpassword.value;
var reenterpassword=document.form.confirmpassword.value;
alert(oldpassword_actual);
alert(oldpassword_entered);
alert(newpassword);
alert(reenterpassword);
return false;
}
</script>
</head>
<body align="center">
<form name="form" action="" method="post">
Enter old p开发者_如何转开发assword<input type="password" name="oldpassword"></br></br>
Enter new password<input type="password" name="newpassword"></br></br>
Reenter new password<input type="password" name="confirmpassword"></br></br>
<%
oldpassword=(String)session.getAttribute("Password");
%>
<input type="submit" name="confirm" value="Confirm" onclick="return redirect()">
</form>
</body>
</html>
when the alert box pops up..it gives a null value for the jsp variable..
It's because the JSP variable is been printed as JavaScript variable before the form is submitted.
Short explanation: JSP runs at webserver, produces HTML/CSS/JS, webserver sends it to webbrowser, HTML/CSS/JS runs at webbrowser. Long explanation: communication between Java/JSP and JavaScript.
How to solve this: replace JavaScript by a Java Servlet. JavaScript isn't the right tool for the job of request processing.
You need to move:
<%
oldpassword=(String)session.getAttribute("Password");
%>
To the top of your code (or somewhere above the line: var oldpassword_actual="<%= oldpassword %>";)
加载中,请稍侯......
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