Hidden value assigned in js lost after postback

Question

Here's my problem. I have a hidden field whose value I change through a javascript method. The problem is after postback the value is lost.

How can I persist the value after postback?

Thanks!

.aspx File

<asp:HiddenField ID="HiddenField1" runat="server" />
<asp:Button ID="BtnGuardar" runat="server" OnClick="BtnGuardar_Click" OnClientClick="return GridUpdateInfoOK()" />

.js file

document.getElementById('<%= HiddenField1.ClientID %>').value = 'TEST';

.aspx.cs file

protected void BtnGuardar_Click(object sender, EventArgs e)
{
    String test = HiddenField1.Value;
}

Answer 1

You don't need to have the hidden input run at server. You can do:

<input type="hidden" id="HiddenInput" name="HiddenInput" value="" />

Then when you post back you can access it like that:

protected void BtnGuardar_Click(object sender, EventArgs e)
{
    String test = Request.Form["HiddenInput"];
}

Answer 2

That doesn't work like that. The value is not present since the PageLoad, so won't be postbacked. Try using a TextBox with style="display:none".

Answer 3

Please use

<asp:HiddenField ID="HiddenField1" runat="server" EnableViewState="true"/>

Then we will get the value after postback.

All the properties of HiddenField are as bellow:

<asp:HiddenField
    EnableTheming="True|False"
    EnableViewState="True|False"
    ID="string"
    OnDataBinding="DataBinding event handler"
    OnDisposed="Disposed event handler"
    OnInit="Init event handler"
    OnLoad="Load event handler"
    OnPreRender="PreRender event handler"
    OnUnload="Unload event handler"
    OnValueChanged="ValueChanged event handler"
    runat="server"
    SkinID="string"
    Value="string"
    Visible="True|False"
/>