code: function validateField(fieldId, submission, sectionIndex, cb) {
        init();
  
        if (_.isFunction(sectionIndex)) {
          cb = sectionIndex;
          sectionIndex = 0;
        }
  
        var err = initSubmission(submission);
        if (err) {
          return cb(err);
        }
  
        var submissionField = submissionFieldsMap[fieldId][sectionIndex];
        var fieldDef = fieldMap[fieldId];
  
        getFieldValidationStatus(submissionField, fieldDef, null, function(err, res) {
          if (err) {
            return cb(err);
          }
          var ret = {
            validation: {}
          };
  
          assignValidationResponse(fieldId, sectionIndex, ret.validation, res);
          return cb(undefined, ret);
        });
      }
docs: validate only field values on validation (no rules, no repeat checking)
  res:
  "validation":{
  "fieldId":{
  "fieldId":"",
  "valid":true,
  "errorMessages":[
  "length should be 3 to 5",
  "should not contain dammit"
  ]
  }
  }