required JS for Phonenumber validation accept + -

Text field validation keep data after submit use required="required"
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<input type="text" id="" name="phone" onkeypress="return onlyNos(event,this);" maxlength="15" required="required">

<script language="Javascript" type="text/javascript">

        function onlyNos(e, t) {

            try {

                if (window.event) {

                    var charCode = window.event.keyCode;

                }

                else if (e) {

                    var charCode = e.which;

                }

                else { return true; }

                if (charCode > 31 && (charCode < 48 || charCode > 57) && charCode > 43 && charCode > 45) {

                    return false;

                }

                return true;

            }

            catch (err) {

                alert(err.Description);

            }

        }



    </script>