FormNotifications.js

EndDateValidationWithFormNotification: function (executionContext) {
    var formContext = executionContext.getFormContext();
    var startDate = formContext.getAttribute("my_startdate").getValue();
    var endDate = formContext.getAttribute("my_enddate").getValue();
        
    if(endDate > startDate)
        formContext.ui.clearFormNotification("EndDateValidation");
    else{
    formContext.ui.setFormNotification("End Date must be bigger than Start Date", "ERROR", "EndDateValidation");
    formContext.getAttribute("my_enddate").setValue(null);
    }
  },
      
 EndDateValidationWithIsValid: function (executionContext) {    
    var formContext = executionContext.getFormContext();
    var startDate = formContext.getAttribute("my_startdate").getValue();
    var endDate = formContext.getAttribute("my_enddate").getValue();
    var valid = endDate > startDate;
     
    formContext.getAttribute("my_enddate").setIsValid(valid, "End Date must be bigger than Start Date");
    formContext.getAttribute("my_enddate").setValue(null);
  },