How to pass variable from jquery to code behind (C#)?

Question

Here is my code, but it doesn't work (code behind gets empty string): `

<head id="Head1" runat="server">
<title>Pass Javascript Variables to Server</title>
     <script type="text/javascript">             // Second Step
         function f() {
             $("[id$='inpHide']").val("My JavaScript Value");

         }
    </script>
</head>

<body onload="SetHiddenVariable()">
    <form id="form1" runat="server">
    <div>  
        <input id="inpHide" type="hidden" runat="server" />  
        <asp:Button ID="btnJSValue" Text="Click" runat="server" OnClientClick="f"/>
        <asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
    </div>
    </form>
</body>

`

ShankarSangoli · Accepted Answer · 2011-08-09 14:37:44Z

1

There were couple of issues in your code. The parenthesis were missing while calling f function in onClientClick and if the element has id you can just use the id to select it with #

<head id="Head1" runat="server">
<title>Pass Javascript Variables to Server</title>
     <script type="text/javascript">             // Second Step
         function f() {
             $("input[id*='inpHide']").val("My JavaScript Value");
         }
    </script>
</head>

<body>
    <form id="form1" runat="server">
    <div>  
        <input id="inpHide" type="hidden" runat="server" />  
        <asp:Button ID="btnJSValue" Text="Click" runat="server" OnClientClick="f()"/>
        <asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
    </div>
    </form>
</body>

edited Aug 9, 2011 at 14:37

answered Aug 9, 2011 at 14:32

ShankarSangoli

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17 Comments

Johnny5 Over a year ago

His input is runat="server". In this example the ClientID will be "inpHide", but in a real world case it may be inside other naming container. I guess that's why he used the end-with syntax $("[id$='inpHide']")

ShankarSangoli Over a year ago

@Nickolay - It was already part of your code snippet. It will execute that method on page load. I have removed it now since you are not aware of that method so need of it.

ShankarSangoli Over a year ago

Looking at his markup it is quite simple but yest if it inside a control or master page it should be client id.

ShankarSangoli Over a year ago

*= will search within the id, it should work fine. Can you check what is the id of this input element when it is rendered on the page.

ShankarSangoli Over a year ago

View source of the page. Right click on the page and just click on view source or view page source whatever option you could see.

|

Sean McMillan · Accepted Answer · 2011-08-09 14:36:12Z

1

Your <input> tag needs a name attribute, or it won't be posted.

answered Aug 9, 2011 at 14:36

Sean McMillan

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Comments

Johnny5 · Accepted Answer · 2011-08-09 14:39:27Z

0

The response from Sean McMillan is right, but I think you also need to change this :

<asp:Button ID="btnJSValue" Text="Click" runat="server" OnClientClick="f"/>

to

<asp:Button ID="btnJSValue" Text="Click" runat="server" OnClientClick="f();"/>

answered Aug 9, 2011 at 14:39

Johnny5

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3 Comments

Johnny5 Over a year ago

Are you sure your f function is being called? If you put an alert into it?

Rougher Over a year ago

if after $("input[id*='inpHide']").val("My JavaScript Value"); set alert("something") it doesn't call alert... –

Johnny5 Over a year ago

Then your line is causing an error, check the error console in firefox (ctrl+shift+J).

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