Default button click on enter use javascript

<script type="text/javascript">
    if (document.addEventListener) {//if Firefox
        document.addEventListener("keypress", fireFoxHandler, true);
       
    } else {
       
        document.attachEvent("onkeyup", ieHandler);
    }
   
    function fireFoxHandler(evt) {
        if (evt.keyCode == 13) {
            document.getElementById("btnSave").click();
           
        }
    }

    function ieHandler(evt) {
        if (evt.keyCode == 13) {
            document.getElementById("btnSave").click();
        }
    }

</script>

<asp:Button ID="btnSave" ValidationGroup="Submit" runat="server" Text="Save" OnClick="btnSave_Click"
                    CssClass="save_btn" ClientIDMode="Static" />