import { InputValidationRule } from 'vuetify' ; const requiredErrorMessage = 'required.' ; param value export const requiredRule = value => { if ( isNullOrUndefined ( value ) ) { return requiredErrorMessage ; } if ( typeof value === 'string' && value . length === 0 ) { return requiredErrorMessage ; } return true ; } ; export function isNullOrUndefined ( value ) { return value == null || value === undefined ; }