Watermark TextBox using JavaScript

<script type = "text/javascript">

    var defaultText = "Enter your text here";

    function WaterMark(txt, evt)

    {

        if(txt.value.length == 0 && evt.type == "blur")

        {

            txt.style.color = "gray";

            txt.value = defaultText;

        }

        if(txt.value == defaultText && evt.type == "focus")

        {

            txt.style.color = "black";

            txt.value="";

        }

    }

</script>

---------------------------

<asp:TextBox ID="TextBox1" runat="server" Text = "Enter your text here"

    ForeColor = "Gray" onblur = "WaterMark(this, event);"

    onfocus = "WaterMark(this, event);">

</asp:TextBox>

---------------------------OR-----------------------

TextBox1.Attributes.Add("onblur", "WaterMark(this, event);");

TextBox1.Attributes.Add("onfocus", "WaterMark(this, event);");