How to get HiddenField value in asp.net code-behind

Question

How to get HiddenField value in asp.net code-behind？ Thanks in advance! ``` public partial class ReadCard : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Response.Cache.SetCacheability(System.Web.HttpCacheability.NoCache); } protected void Button1_Click(object sender, EventArgs e) { this.ClientScript.RegisterStartupScript(this.GetType(), "MyClick ", " "); string b= HiddenField1.Value; //How to get the value "123"?? } } ``` aspx: ```

Accepted Answer

The client ID isn't necessarily the same as the server ID (unless you're using `CliendIDMode=Static`. You can insert a server tag to get the client ID.

Note also that you have to put the script inside a `document.ready` tag, or put the script at the bottom of the page -- otherwise the script won't find HiddenField1, as it will not have been loaded into the DOM yet.

```
$(document).ready(function() {
    $("<%= HiddenField1.ClientID %>").val("123");
});
```

How to get HiddenField value in asp.net code-behind

Solution

Problem