HiddenField

@inherits ControlComponent
<p>Please enter a value and click the submit button.</p>

<asp.TextBox ID="ValueTextBox" />

<br />
<br />

<asp.Button OnClientClick="$('#ValueHiddenField').val($('#ValueTextBox').val());"
                                            OnClick="this.SubmitBtn_Click">Submit</asp.Button>

<br />

<asp.Label @ref="this.message" />

<asp.HiddenField @ref="this.valueHiddenField" ID="ValueHiddenField"
                                            Value="" />

@code {
                                            private Label message;
                                            private HiddenField valueHiddenField;

                                            protected void SubmitBtn_Click(object sender, EventArgs e)
    {
                                            // Display the value of the HiddenField control.
        message.Text = "The value of the HiddenField control is " + valueHiddenField.Value + ".";
    }
}