Show Button on typing in TextBox using JavaScript in ASP.Net

Hi micah,

Check this example. Now please take its reference and correct your code.

HTML

<script type="text/javascript">
    function ShowButton(ele) {
        document.getElementById('btnSave').style.display = ele.value.length > 0 ? "block" : "none";
    }
</script>
<asp:TextBox runat="server" ID="txtName" onkeyup="ShowButton(this)" />
<asp:Button ID="btnSave" Text="Save" runat="server" Style="display: none;" />

Screenshot