number static method

FormFieldValidator<String> number(
  1. String m
) 
 Validatorless.number('Value not a number')

Implementation

static FormFieldValidator<String> number(String m) {
  return (v) {
    if (v?.isEmpty ?? true) return null;
    if (double.tryParse(v!) != null)
      return null;
    else
      return m;
  };
}