How to restrict users to put a future date in Netsuite custom date field?

To restrict user from adding a future date in shipment receiving date. The field should be either today or any past date but not future.

The below validation function that is executed when a field is changed by a user or client call.

function validateField(context) {
    var curRec = context.currentRecord;
    var fieldName = context.fieldId;
    if (fieldName === 'date') { //replace "date" with your field id
      var recDate = curRec.getValue({fieldId: fieldName});
      var today = new Date();
      if (recDate > today){
        alert('You cannot enter a future date');
        curRec.setValue({
          fieldId: 'date',
          value: null
        });
      }
      return true;
    }