Access variablea of javascript in .aspx.vb file - asp.net

Question

I want to access variables defined in Javascript in.aspx file to .aspx.vb file
How can i access variables in .aspx.vb file?
<script type="text/javascript" language="javascript">
var c=0;
var m=0;
var h=0;
var t;
var timer_is_on=0;
function startTMR()
{
document.getElementById('TimeLable').value=h+":"+m+":"+c;
c=c+1;
if(c==60)
{
c=0;
m=m+1;
if(m==60)
{
m=0;
h=h+1;
}
}
t=setTimeout("startTMR()",1000);
}
function doTimer()
{
if (!timer_is_on)
{
timer_is_on=1;
startTMR();
}
}
This is simple javascript I'm using in my .aspx page
now i want to access the variable h m and c in .aspx.vb page how to do that?

Answer 1

You'll need to save that javascript variable into a hidden input, which will post with your form when you do a postback. You'll be able to access the value via:
string value = Request.Form["hiddenName"];
Assuming you declare your hidden input like this:
<input type="hidden" id="hiddenValue" name="hiddenName" />
You can set this value like this with native JavaScript:
document.getElementById("hiddenValue").value = "12";
or with jQuery like this:
$("#hiddenValue").val("12");
If you'd like to make sure this hidden input is automatically saved to the JavaScript variable x before you post back, you could do the following with jQuery
$("#form1").submit(function () {
$("#hiddenValue").val(x);
});
Or this with native JavaScript:
document.getElementById("form1").addEventListener("submit", function () {
document.getElementById("hiddenValue").value = x;
});
If you're not using jQuery, and you opt for this native option, just make sure you put the script at the bottom of the body section; do not put this script in the head, since the dom is not formed yet, and you will get a null error.
And obviously this all assumes your form element looks like this:
<form id="form1" runat="server">
if yours has a different id, then adjust accordingly.