form-lib-10.md

const asyncValidate = (values) => { 
  // ... returns a promise which does the async operation of validating the field. 
}; 

const renderField = ({ meta }) => { 
  /* asyncValidating flag in field meta prop to know the status of ongoing async validating action */ 
  
  const { asyncValidating } = meta; // ... rendering of field 
}; 

//... return of HOC 
return reduxForm({ 
  asyncValidate, 
  /* option to specify the field of which "blurring" will trigger asyncValidate method */ 
  asyncBlurFields: ['userName'], 
});