How to get text from textarea Textbox using javascript

   <div class="box-c>
        <textarea cols="80" id="editor1" name="editor1" rows="10"  runat="server" clientidmode="Static"
            style="width: 900px;">
</textarea>
        <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="editor1"
            SetFocusOnError="true" Display="None" ErrorMessage="Enter Template" ValidationGroup="abc"></asp:RequiredFieldValidator>
        <asp:ValidatorCalloutExtender ID="RequiredFieldValidator1_ValidatorCalloutExtender"
            runat="server" TargetControlID="RequiredFieldValidator1">
        </asp:ValidatorCalloutExtender>
    </div>



I tried using this code but i am not getting value :

        var msg = document.getElementById('editor1').innerHTML;
        alert(msg);