Below script is a generic validation which will show for error if field is having anything except numeric value

function ValidateOnlyNumeric(context) {
    var fieldname = context.getEventSource().getName();
    var phone = Xrm.Page.getAttribute(fieldname).getValue();
    if (checkFormat(phone)) {
    } else {
        Xrm.Page.getControl(fieldname).setNotification("Please enter only numeric characters");
function checkFormat(phone) {
    var regex = /^\d+$/;
    if (regex.test(phone)) {
        return true;
    } else {
        return false;

To enable it for any field just register it on change of the required field with function name “ValidateOnlyNumeric” and check “Pass execution context as first parameter ” and save an publish it will start working

Hope it helps

Happy Coding 😊