Adding multiple colors to single cell content using j script in asp.net

Here i bind data to GridView from database
Default.aspx

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" OnRowDataBound="GridView1_RowDataBound">

            <Columns>

                <asp:TemplateField HeaderText="Customer">

                    <ItemTemplate>

                        <asp:Label runat="server" ID="lblCustomer" Text='<%# Eval("Customer") %>'></asp:Label>

                    </ItemTemplate>

                </asp:TemplateField>

                <asp:TemplateField HeaderText="ContactName">

                    <ItemTemplate>

                        <asp:Label runat="server" ID="lblContactName" Text='<%# Eval("ContactName") %>'></asp:Label>

                    </ItemTemplate>

                </asp:TemplateField>

                <asp:TemplateField HeaderText="ContactTitle">

                    <ItemTemplate>

                        <asp:Label runat="server" ID="lblContactTitle" Text='<%# Eval("ContactTitle") %>'></asp:Label>

                    </ItemTemplate>

                </asp:TemplateField>

            </Columns>

        </asp:GridView>

Code in Default.aspx.cs

SqlConnection con = new SqlConnection("Data Source=INHYDSPARSHIMON\\SQL2012;Initial Catalog=SMPL;User ID=sa;Password=******");

            SqlDataAdapter da = new SqlDataAdapter("Select Customer,ContactName,ContactTitle from tbl_Customer", con);

            DataSet ds = new DataSet();

            da.Fill(ds, "tbl");

            GridView1.DataSource = ds;

            GridView1.DataBind();

//Call javascript function in code behind

ScriptManager.RegisterStartupScript(this, GetType(), "displayalertmessage", "getdata();", true); 

Sample.js

function getdata() {

    var obj = document.getElementById('GridView1_lblContactName_0').innerText;

    var slp = [];

    slp = obj.split(' ');

    slp[0].fontcolor("green");

    for (var i = 0; i < slp.length; i++) {

        document.getElementById('GridView1_lblContactName_0').innerHTML = slp[0].fontcolor("green");

        document.getElementById('GridView1_lblContactName_0').innerHTML += slp[1].fontcolor("red");

    }

}

Output