Get Label text value into javascript variable

Question

I am very new to javascript but unfortunately it is what I have to use for a thermometer chart that I'm using. I need to get the value of an ASP label text and then store that into a javascript variable which will be used to set the chart value.

For some reason it is not storing the value at all and the chart obviously doesn't have the value needed. Again I am extremely new to javascript so please be nice. :) Here is what I have so far.

Here is part of the ASPX page:

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
<script>
    window.onload = function () {
        // Create the Thermometer chart. The arguments are: the canvas ID, the minimum,
        // the maximum and the indicated value.

        var grossSales = $('#<%= MtdLBL.ClientID %>').next().text;
        var thermometer = new RGraph.Thermometer('salesThermometer', 0, 180000, parseInt(grossSales.valueOf))

        // Configure the thermometer chart to look as you want.
                    .Set('chart.gutter.left', 45)
                    .Set('chart.gutter.right', 45)
                    .Set('chart.colors', ['rgba(255,0,0,1)'])
                    .Set('chart.units.pre', '$')
        // Now call the .Draw() method to draw the chart.
                    .Draw();
    }
            </script>
<link href="Charts/RGraph/demos/demos.css" rel="stylesheet" type="text/css" />
<script src="Charts/RGraph/libraries/RGraph.common.core.js" type="text/javascript"></script>
<script src="Charts/RGraph/libraries/RGraph.thermometer.js" type="text/javascript"></script>
</asp:Content>

And this is from the code-behind:

protected void Page_Load(object sender, EventArgs e)
{
    if (Session["TeamID"] == null || Session["TeamID"] == "")
    {
        Response.Redirect("~/Default.aspx");
    }
    else
    {
        //Populate department average
        double deptAvg = achievementData.DeptAverage();
        DeptAvgValueLBL.Text = deptAvg.ToString("P0");

        //Get sales data
        Sales getSalesData = new Sales();
        MtdLBL.Text = getSalesData.GrossSalesByTeam(Session["TeamID"].ToString());
    }
}

Answer 1

var grossSales = $('#<%= MtdLBL.ClientID %>').text();

Note parentheses; text is a function, not a simple value. The next() is out of place unless you want the following control, which doesn't seem right.