diff --git a/package.json b/package.json
index 5acc05b..875ac29 100644
--- a/package.json
+++ b/package.json
@@ -18,6 +18,7 @@
     "test": "run-s build test:*",
     "test:unit": "nyc --silent ava",
     "watch": "run-s clean build:main && run-p \"build:main -- -w\" \"test:unit -- --watch\"",
+    "watch-tsc": "tsc --watch",
     "cov": "run-s build test:unit cov:html && opn coverage/index.html",
     "cov:html": "nyc report --reporter=html",
     "cov:send": "nyc report --reporteyarnr=lcov > coverage.lcov && codecov",
diff --git a/src/lib/dataInference.ts b/src/lib/dataInference.ts
index 15322c2..e755dd0 100644
--- a/src/lib/dataInference.ts
+++ b/src/lib/dataInference.ts
@@ -1,5 +1,5 @@
 import dayjs from 'dayjs';
-import { get, isFinite, isNaN, isNull, isUndefined, keys } from 'lodash';
+import { get, isFinite, isNaN, isNull, isUndefined, keys, isDate, isString } from 'lodash';
 import {
   CategoricalDatum,
   ContinuousDatum,
@@ -10,9 +10,40 @@ import {
 } from '../types/types';
 import { fromPairs } from './parseObjects';
 import { getAllKeys } from './stats';
-
-import CustomParseFormat from 'dayjs/plugin/customParseFormat'; // load on demand
-dayjs.extend(CustomParseFormat); // use plugin
+import customParseFormat from 'dayjs/plugin/customParseFormat';
+dayjs.extend(customParseFormat);
+
+// references:
+// https://day.js.org/docs/en/parse/string-format
+// https://day.js.org/docs/en/display/format
+export const DATE_FORMATS = [
+  'YYYY-MM-DD',
+  'YYYY-MM-D',
+  'YYYY-M-DD',
+  'YYYY-M-D',
+
+  'YYYY-MM-DD HH:mm',
+  'YYYY-MM-DD HH:mm[Z]',
+  'YYYY-MM-DD[T]HH:mm',
+  'YYYY-MM-DD[T]HH:mm[Z]',
+  
+  'YYYY-MM-DD HH:mm:ss',
+  'YYYY-MM-DD HH:mm:ss[Z]',
+  'YYYY-MM-DD[T]HH:mm:ss',
+  'YYYY-MM-DD[T]HH:mm:ss[Z]',
+
+  'YYYY-MM-DD HH:mm:ss.SSS',
+  'YYYY-MM-DD HH:mm:ss.SSS[Z]',
+  'YYYY-MM-DD[T]HH:mm:ss.SSS',
+  'YYYY-MM-DD[T]HH:mm:ss.SSS[Z]', // ISO8601
+
+  'YYYY-MM-DD HH:mm:ss A',
+  'YYYY-MM-DD HH:mm:ss a',
+  
+  // these two formats don't work
+  // 'YYYY-MM-DD HH:mm:ssZ', // 2013-02-08 09:00:00+07:00
+  // 'YYYY-MM-DD HH:mm:ssZZ', // 2013-02-08 09:00:00-0700
+];
 
 export type GenericDatumValue = number | string | boolean | null;
 
@@ -62,27 +93,28 @@ export function detectValue(
   if (!value || isNull(value) || typeof value === 'boolean') {
     return 'unknown';
   }
-
   if (inferIsNumber(value)) {
     return 'continuous';
-  } else if (typeof value === 'string' && isFormatDateValid(value, parser)) {
+  } else if (isDate(value) || (isString(value) && isFormatDateValid(value, parser))) {
     return 'date';
   } else {
     return 'categorical';
   }
 }
 
+function isValidDate(dateString: string, formats: string[]): boolean {
+  const strictMode = true
+  // @ts-ignore: necessary because of strictMode parameter: `Argument of type 'true' is not assignable to parameter of type 'string | undefined'.`
+  return formats.some(format => dayjs(dateString, format, strictMode).isValid())
+}
+
 export function isFormatDateValid(
   value: string,
   parser?: ParserFunction
 ): boolean {
   if(!inferIfStringIsNumber(value[0])) return false
 
-  // this will match yyyy-mm-dd and also yyyy-m-d
-  const regDate = /^([1-9][0-9]{3})\-(0?[1-9]|1[012])\-(0?[1-9]|[12][0-9]|3[01])$/;
-  // TODO: add other regex to accept also other date formats
-
-  const isFormatDateValid = regDate.test(value.toString());
+  const isFormatDateValid = isValidDate(value, DATE_FORMATS);
 
   // NOTE: we assume that if the user has written a parser, then the dates are in the correct format
   return isFormatDateValid || !isUndefined(parser);
diff --git a/src/lib/test/dataInference.spec.ts b/src/lib/test/dataInference.spec.ts
index 9960522..2905fdb 100644
--- a/src/lib/test/dataInference.spec.ts
+++ b/src/lib/test/dataInference.spec.ts
@@ -1,5 +1,7 @@
 import test from 'ava';
 import dayjs from 'dayjs';
+import customParseFormat from 'dayjs/plugin/customParseFormat';
+dayjs.extend(customParseFormat);
 import {
   autoInferenceType,
   detectValue,
@@ -67,19 +69,47 @@ test('isDateValid', t => {
   const defaultParser = (d: string) => dayjs(d, 'YYYY-MM-DD').unix();
 
   t.is(isFormatDateValid('1900-10-23'), true);
-  t.is(isFormatDateValid('2002-5-5'), true);
-  t.is(isFormatDateValid('2008-09-31'), true);
-  t.is(isFormatDateValid('1600-12-25'), true);
   t.is(isFormatDateValid('1942-11-1'), true);
-  t.is(isFormatDateValid('2000-10-10'), true);
-  t.is(isFormatDateValid('2018-02-29'), true); // this day doesn't exist but we check only the date format
-  t.is(isFormatDateValid('2017-02-30'), true); // this day doesn't exist but we check only the date format
-  t.is(isFormatDateValid('2020-04-31'), true); // this day doesn't exist but we check only the date format
+  t.is(isFormatDateValid('2002-5-15'), true);
+  t.is(isFormatDateValid('2000-01-10'), true);
+
+  t.is(isFormatDateValid('2020-05-01 09:35'), true);
+  t.is(isFormatDateValid('2020-05-01 09:35Z'), true);
+  t.is(isFormatDateValid('2020-05-01T09:35'), true);
+  t.is(isFormatDateValid('2020-05-01T09:35Z'), true);
+
+  t.is(isFormatDateValid('2020-05-01 09:35:20'), true);
+  t.is(isFormatDateValid('2019-01-15 13:12:29'), true);
+  t.is(isFormatDateValid('2020-05-01 09:35:20Z'), true);
+  t.is(isFormatDateValid('2020-05-01T09:35:20'), true);
+  t.is(isFormatDateValid('2020-05-01T09:35:20Z'), true);
+
+  t.is(isFormatDateValid('2020-05-01 09:35:20.000'), true);
+  t.is(isFormatDateValid('2020-05-01 09:35:20.000Z'), true);
+  t.is(isFormatDateValid('2020-05-01T09:35:20.000'), true);
+  t.is(isFormatDateValid('2020-05-01T09:35:20.000Z'), true);
+  t.is(isFormatDateValid('2020-05-13T08:24:45.701Z'), true);
+  t.is(isFormatDateValid(new Date().toISOString()), true);
+
+  t.is(isFormatDateValid('2016-01-01 11:31:23 AM'), true);
+  t.is(isFormatDateValid('2016-01-01 11:31:23 am'), true);
+  t.is(isFormatDateValid('2016-01-01 23:31:23 pm'), true);
+
   t.is(isFormatDateValid('17-02-2019', rightParser), true);
   t.is(isFormatDateValid('17-02-2019', wrongParser), true); // this shouldn't be right but we assume that if the user has written a parser, then the dates are in the correct format
   t.is(isFormatDateValid('17-02-2019', defaultParser), true); // this shouldn't be right but we assume that if the user has written a parser, then the dates are in the correct format
 
-  t.is(isFormatDateValid('2019-01-15 13:12:29.0'), false);
+  // t.is(isFormatDateValid('2013-02-08 09:00:00+01:00'), true);
+  // t.is(isFormatDateValid('2013-02-08 09:00:00+01:30'), true);
+  // t.is(isFormatDateValid('2013-02-08 09:00:00+0100'), true);
+  // t.is(isFormatDateValid('2013-02-08 09:00:00-01:00'), true);
+  // t.is(isFormatDateValid('2013-02-08 09:00:00-0100'), true);
+
+  t.is(isFormatDateValid('cat-1'), false);
+  t.is(isFormatDateValid('2017-02-30'), false); 
+  t.is(isFormatDateValid('2020-04-31'), false); 
+  t.is(isFormatDateValid('2018-02-29'), false); 
+  t.is(isFormatDateValid('2008-09-31'), false);
   t.is(isFormatDateValid('17-02-2019'), false);
   t.is(isFormatDateValid('0000-01-01'), false);
   t.is(isFormatDateValid('0100-10-23'), false);
@@ -87,7 +117,20 @@ test('isDateValid', t => {
   t.is(isFormatDateValid('1942-11-0'), false);
   t.is(isFormatDateValid('1942-00-25'), false);
   t.is(isFormatDateValid('2000-10-00'), false);
-  t.is(isFormatDateValid('cat-1'), false);
+  t.is(isFormatDateValid('2019-01-15 24:00:00'), false);
+  t.is(isFormatDateValid('2019-01-15 23:60:00'), false);
+  t.is(isFormatDateValid('2019-01-15 23:59:60'), false);
+  t.is(isFormatDateValid('2019-01-15 13:12:29.0'), false);
+  t.is(isFormatDateValid('2020-05-01 01:01:01.12'), false);
+  t.is(isFormatDateValid('2016-01-01 11:31:23 PM'), false);
+  t.is(isFormatDateValid('2020-05-01 00'), false);
+  t.is(isFormatDateValid('2020-02-31'), false);
+  t.is(isFormatDateValid('2016/01/01'), false);
+  t.is(isFormatDateValid('2020-05-01 01:60:00'), false);
+  t.is(isFormatDateValid('2020-05-01 60'), false);
+  t.is(isFormatDateValid('2020-05-01 '), false);
+  t.is(isFormatDateValid(new Date().toString()), false);
+  t.is(isFormatDateValid('Wed May 13 2020 10:25:23 GMT+0200 (Central European Summer Time)'), false);
 });
 
 // ----------------------------------------------------------
diff --git a/tslint.json b/tslint.json
index ad9677a..6452cf4 100644
--- a/tslint.json
+++ b/tslint.json
@@ -25,12 +25,14 @@
     "no-class": true,
     "no-mixed-interface": false,
     "no-expression-statement": [
-      true,
+      false,
       { "ignore-prefix": ["console.", "process.exit"] }
     ],
     "no-if-statement": false,
     /* end tslint-immutable rules */
 
-    "ordered-imports": false
+    "ordered-imports": false,
+    "curly": false,
+    "no-shadowed-variable": false
   }
 }
diff --git a/yarn.lock b/yarn.lock
index 5ad7d5d..669dd58 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1603,9 +1603,9 @@ dateformat@^3.0.0:
   integrity sha512-jyCETtSl3VMZMWeRo7iY1FL19ges1t55hMo5yaam4Jrsm5EPL89UQkoQRyiI+Yf4k8r2ZpdngkV8hr1lIdjb3Q==
 
 dayjs@^1.8.13:
-  version "1.8.13"
-  resolved "https://registry.yarnpkg.com/dayjs/-/dayjs-1.8.13.tgz#51b5cdad23ba508bcea939a853b492fefb7fdc47"
-  integrity sha512-JZ01l/PMU8OqwuUs2mOQ/CTekMtoXOUSylfjqjgDzbhRSxpFIrPnHn8Y8a0lfocNgAdBNZb8y0/gbzJ2riQ4WQ==
+  version "1.8.27"
+  resolved "https://registry.yarnpkg.com/dayjs/-/dayjs-1.8.27.tgz#a8ae63ee990af28c05c430f0e160ae835a0fbbf8"
+  integrity sha512-Jpa2acjWIeOkg8KURUHICk0EqnEFSSF5eMEscsOgyJ92ZukXwmpmRkPSUka7KHSfbj5eKH30ieosYip+ky9emQ==
 
 debug@^2.1.2, debug@^2.2.0, debug@^2.3.3:
   version "2.6.9"