问AJAX UpdatePanel中不显示JavaScript图表

EN

<form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server" />
    <asp:UpdatePanel runat="server" id="UpdatePanel1" UpdateMode="Conditional" >
        <ContentTemplate>
          <asp:Button ID="btnShowData" runat="server" Text="Show Data" OnClick="btnShowData_Click" />
          <br/>
          <canvas id="myChart" width="400" height="250"></canvas>                    
        </ContentTemplate>
    </asp:UpdatePanel>
</form>

protected void btnShowData_Click(object sender, EventArgs e)
{
    //Run method to get data from SQL database, which is converted to string and passed to JavaScript to create the chart.

    string X = stringArrayromDatabase;
    string scriptText = "<script type=text/javascript> chartFunction(" + stringArrayFromDatabase + ") </script>";

    //This code will work, meaning I've done things correctly with the RegisterStartupScriptmethod:
    ScriptManager.RegisterStartupScript(this, this.GetType(), "", "alert('Hello')", true);

    //Upon running this code, I expect my JavaScript chart will appear in the web page but it doesn't:
    ScriptManager.RegisterStartupScript(this, this.GetType(), "", scriptText, true);
}

function chartFunction(stringArrayFromDatabase) {
    var canvas = document.getElementById('myChart');
    var data = {
        labels: ["January", "February", "March", "April", "May"],
        datasets: [
            {
                label: "My First dataset",
                borderColor: "rgba(75,192,192,1)",
                data: stringArrayFromDatabase,
            }
        ]
    };
    var option = {
        showLines: true
    };
    var myLineChart = new Chart(canvas,{
        type:'line',
        data:data,
      options:option
    }