$("#chartModal").keypress( function (e) {
if (e.which != 8 && e.which != 0 && e.which != 43 && e.which != 45 && e.which != 46 && (e.which < 48 || e.which > 57)) {
return false;
}
});
This accept +, - & . in between the number, which is not a number.