Assign (Set) value to HTML TextBox on ASP.Net Button Click using C# and VB.Net

Hi moquamar,

Please refer below sample.

HTML

<input id="MyInputBox" name="MyInputBox" type="text" runat="server" />
<br />
<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="Submit" />

Code

C#

protected void Submit(object sender, EventArgs e)
{
    MyInputBox.Value = "ASPSnippets";
}

VB.Net

Protected Sub Submit(ByVal sender As Object, ByVal e As EventArgs)
    InputBox.Value = "ASPSnippets"
End Sub

Screenshot