Call ASP.Net Button Click event using JavaScript from code behind using C# and VB.Net

Hi taruni,

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

HTML

<asp:Button ID="btnSubmit" Text="Submit" runat="server" OnClick="Btnformsubmit_Click" Style="display: none;" />
<div id="dvPopup" style="display: none;">
    <asp:TextBox runat="server" ID="txtId" /><br />
    <asp:TextBox runat="server" ID="txtName" /><br />
    <asp:TextBox runat="server" ID="txtCountry" />
</div>
<script type="text/javascript">
    function PopulateTextBox(id, name, country) {
        document.getElementById('txtId').value = id;
        document.getElementById('txtName').value = name;
        document.getElementById('txtCountry').value = country;
    }

    function ShowPopup() {
        document.getElementById('dvPopup').style.display = "block";
    }
</script>

Namespaces

C#

using System.Data;
using System.Text;

VB.Net

Imports System.Data
Imports System.Text

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3]
        {
            new DataColumn("Id"),
            new DataColumn("Name"),
            new DataColumn("Country")
        });
        dt.Rows.Add(1, "Mudassar Khan", "India");
        if (dt.Rows.Count > 0)
        {
            string id = dt.Rows[0]["Id"].ToString();
            string name = dt.Rows[0]["Name"].ToString();
            string country = dt.Rows[0]["Country"].ToString();

            StringBuilder sb = new StringBuilder();
            sb.Append("<script type = 'text/javascript'>");
            sb.Append("window.onload=function(){");
            sb.Append("PopulateTextBox('" + id + "','" + name + "','" + country + "');");
            sb.Append("ShowPopup();");
            sb.Append("document.getElementById('btnSubmit').click();");
            sb.Append("};");
            sb.Append("</script>");
            ClientScript.RegisterStartupScript(this.GetType(), "message", sb.ToString());
        }
    }
}

protected void Btnformsubmit_Click(object sender, EventArgs e)
{
    ClientScript.RegisterStartupScript(this.GetType(), "message", "alert('Button clicked.')", true);
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim dt As DataTable = New DataTable()
        dt.Columns.AddRange(New DataColumn(2) {
                            New DataColumn("Id"),
                            New DataColumn("Name"),
                            New DataColumn("Country")})
        dt.Rows.Add(1, "Mudassar Khan", "India")

        If dt.Rows.Count > 0 Then
            Dim id As String = dt.Rows(0)("Id").ToString()
            Dim name As String = dt.Rows(0)("Name").ToString()
            Dim country As String = dt.Rows(0)("Country").ToString()
            Dim sb As StringBuilder = New StringBuilder()
            sb.Append("<script type = 'text/javascript'>")
            sb.Append("window.onload=function(){")
            sb.Append("PopulateTextBox('" & id & "','" & name & "','" & country & "');")
            sb.Append("ShowPopup();")
            sb.Append("document.getElementById('btnSubmit').click();")
            sb.Append("};")
            sb.Append("</script>")
            ClientScript.RegisterStartupScript(Me.GetType(), "message", sb.ToString())
        End If
    End If
End Sub

Protected Sub Btnformsubmit_Click(ByVal sender As Object, ByVal e As EventArgs)
    ClientScript.RegisterStartupScript(Me.GetType(), "message", "alert('Button clicked.')", True)
End Sub