Is there a way to assign/pass/copy a javascript variable to a server side variable in C#? For the sake of argument, let's say that I was able to parse some JSON for variables that I want to store and assign them on the client (ie. var = FirstName and var = 25 and var = someDateTime, etc) .
2
-
i think you need to be a "little" more specific, I'm going to assume you mean ajax, or do you mean json, or what...dstarh– dstarh2010-10-26 14:27:12 +00:00Commented Oct 26, 2010 at 14:27
-
@dstarh see above, made a couple edits. does this help?locoboy– locoboy2010-10-26 15:07:39 +00:00Commented Oct 26, 2010 at 15:07
Add a comment
|
4 Answers
Javascript variables exist on the client so in order to get those values into the server you'll need to execute a request from the client. You probably want an approach called AJAX. AJAX involves Javascript making requests to the server in the background of your page. You'll set up a C# web page that expects these background requests. If you use a GET request then then place the variables in the query string of your AJAX request to your new C# page. If you want to use a POST request then you'll set parameters in the data that you post to your page.
Libraries like jQuery make this kind of thing pretty simple.
2 Comments
locoboy
how would you implement this?
Dave Aaron Smith
@cfarm54, well, one of the great skills you want to build up as a software developer is being able to figure the details out for yourself. I would start by Googling things like AJAX and jQuery so you can understand them fundamentally. Then when you hit specific dead ends, come back and ask us. As it stands, the question is a little too vague for particularly specific answers, IMHO.
There's no direct way to access variables in client-side code from your server-side code.
An easy way, without writing handlers, ajax posts, etc., to accomplish this is to simply store the java script variable in a hidden text box and retrieve it on your post. You can also write back to the hidden field and feed your script with the value, e.g.
Markup
<asp:HiddenField runat="server" Id="JavascriptValue" value="0">
Script
<script>
var myValue = <%=JavascriptValue.Value%>
</script>
Server-Side
protected void Page_Load(object sender, EventArgs e)
{
string val = JavascriptValue.Value;
}
answered Oct 26, 2010 at 14:29
George Johnston
32.3k29 gold badges130 silver badges177 bronze badges
Write the value to a control (e.g. HiddenField) via JS and read that on the postback.
You can register hidden fields from code-behind on the Page_Load
if (this.Request.Form["myHiddenField"] == null) {
ClientScript.RegisterHiddenField("myHiddenField", ""); }
populate it with a script
ClientScript.RegisterOnSubmitStatement(this.GetType(),
MethodBase.GetCurrentMethod().DeclaringType.Name + "_myHiddenField",
"var res=document.getElementById('myHiddenField');if(res!=null){res.value='some value';}");
and read it on postbacks (also Page_Load)
var myValue = (!IsPostBack)
? null
: this.Request.Form["myHiddenField"];
Comments
what I did is save the javaScript variable in a cookie and then read it from C#.
JavaScript Code:
<script>
$(document).ready(function () {
createCookie("height", $(window).height(), "10");
});
function createCookie(name, value, days) {
var expires;
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
expires = "; expires=" + date.toGMTString();
} else {
expires = "";
}
document.cookie = escape(name) + "=" + escape(value) + expires + "; path=/";
}
</script>
C# Code:
height of browser:@Request.Cookies["height"].Value;
