diff --git a/README.md b/README.md
index d5a5517..08542e9 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,8 @@
 # business-hours.js
-Handle business hours of a restaurant, office or any other business. Highly customizable with lots of features.
+Handle business hours of a restaurant, office or any other business. Highly customizable with lots of features, based on moment.js.
+
+[Demo](https://codesandbox.io/s/github/littletower/business-hours.js/tree/master/example)
 
-[Demo](https://business-hours-example.herokuapp.com/)
 
 [![Travis](https://img.shields.io/travis/littletower/business-hours.js.svg?style=flat-square)]()
 [![Codecov](https://img.shields.io/codecov/c/github/littletower/business-hours.js.svg?style=flat-square)]()
@@ -20,80 +21,82 @@ yarn add business-hours.js
 
 # Configuration
 
-To get started, setup a JSON file where you define the business hours.
-
-`0` stands for `Sunday`<br>
-`1` stands for `Monday` and so on.
+To get started, you'll need to define your business hours in JSON format for every weekday.
 
 You can have 1 to N `from/to` pairs per weekday. If on a given day you are closed, instead of a `from/to` pair, just put `closed`.
 
+In `holidays` you can define on which day the business is closed for holidays. It can be one day (YYYY/MM/DD) or a range (YYYY/MM/DD-YYYY/MM/DD).
+
+Set the desired timezone in `timeZone`, use any `tz` timezone.
+
 ```json
-{
-  "0": [
-    {
-      "from": "10:00",
-      "to": "13:30"
-    },
-    {
-      "from": "17:00",
-      "to": "20:00"
-    },
-    {
-      "from": "21:00",
-      "to": "24:00"
-    }
-  ],
-  "1": [
-    {
-      "from": "10:00",
-      "to": "13:30"
-    },
-    {
-      "from": "18:00",
-      "to": "22:00"
-    }
-  ],
-  "2": "closed",
-  "3": [
-    {
-      "from": "10:00",
-      "to": "13:30"
-    },
-    {
-      "from": "18:00",
-      "to": "22:00"
-    }
-  ],
-  "4": [
-    {
-      "from": "10:00",
-      "to": "13:30"
-    },
-    {
-      "from": "18:00",
-      "to": "22:00"
-    }
-  ],
-  "5": [
-    {
-      "from": "10:00",
-      "to": "13:30"
-    },
-    {
-      "from": "18:00",
-      "to": "22:00"
-    }
-  ],
-  "6": [
-    {
-      "from": "10:00",
-      "to": "13:30"
-    },
-    {
-      "from": "18:00",
-      "to": "22:00"
-    }
-  ]
+"Monday": [
+  {
+    "from": "10:00",
+    "to": "13:30"
+  },
+  {
+    "from": "18:00",
+    "to": "22:00"
+  }
+],
+"Tuesday": "closed",
+"Wednesday": [
+  {
+    "from": "10:00",
+    "to": "13:30"
+  },
+  {
+    "from": "18:00",
+    "to": "22:00"
+  }
+],
+"Thursday": [
+  {
+    "from": "10:00",
+    "to": "13:30"
+  },
+  {
+    "from": "18:00",
+    "to": "22:00"
+  }
+],
+"Friday": [
+  {
+    "from": "10:00",
+    "to": "13:30"
+  },
+  {
+    "from": "18:00",
+    "to": "22:00"
+  }
+],
+"Saturday": [
+  {
+    "from": "10:00",
+    "to": "13:30"
+  },
+  {
+    "from": "18:00",
+    "to": "22:00"
+  }
+],
+"Sunday": [
+  {
+    "from": "10:00",
+    "to": "13:30"
+  },
+  {
+    "from": "17:00",
+    "to": "20:00"
+  },
+  {
+    "from": "21:00",
+    "to": "24:00"
+  }
+],
+"holidays": ["2017/12/11", "2017/12/23-2018/01/02"],
+"timeZone":"Europe/Amsterdam"
 }
 ```
 
@@ -114,9 +117,33 @@ import hoursJson from "./hours.json";
 or it could come from any other endpoint (DB, GraphQL, Firebase...), as long as it's in JSON.
 
 # Example
+To check if your business is currently open:
+```
+let isBusinessOpenNow = businessHours.isOpenNow(); //returns boolean value
+```
+
 Find a whole example in React here [here](example/)
 
+# Doc
+
+Method | Argument | Description
+------ | -------- | -----------
+`isOpenNow` | optional : date | Returns if your business is open or not. If an argument is provided, the method will be executed for the given date.
+`isClosedNow` | optional : date | Returns if your business is closed or not. If an argument is provided, the method will be executed for the given date.
+`willBeOpenOn` | date | Returns if your business will be open on given date.
+`isOpenTomorrow` |  | Returns if your business is open tomorrow.
+`isOpenAfterTomorrow` |  | Returns if your business is open after tomorrow.
+`nextOpeningDate` | optional : boolean | Returns the next opening date. If argument is set to `true`, the next opening date could be today.
+`nextOpeningHour` |  | Returns the next opening hour.
+`isOnHoliday` | optional : date | Returns if your business is closed for holidays.
+`isOnHolidayInDays` | integer | Returns if your business will be closed for holidays in `x` days.
+
+
 # TODOs
-- [ ] use ISO formate for weekday, meaning, starting the week on Monday instead of Sunday
-- [ ] add holidays (single day or range) in ISO (ISO 8601) format YYYY-MM-DD
+- [ ] support after midnight hours, (eg. open from 18:00 to 03:00)
+- [x] Time zones support
+- [x] use ISO format for weekdays, meaning, starting the week on Monday instead of Sunday
+- [x] add holidays (single day or range) in ISO (ISO 8601) format YYYY-MM-DD
+- [ ] support hourly holidays, like business opens from 20:00 instead of 18:00 on a given date.
 - [ ] add always closed on public holidays (country specific)
+- [ ] add localized formatter to display all the business hours
diff --git a/dist/index.js b/dist/index.js
index 3753878..b3165a6 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -2,41 +2,13 @@
 
 var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
 
-var _set_minutes = require("date-fns/set_minutes");
+var _momentTimezone = require("moment-timezone");
 
-var _set_minutes2 = _interopRequireDefault(_set_minutes);
+var _momentTimezone2 = _interopRequireDefault(_momentTimezone);
 
-var _set_hours = require("date-fns/set_hours");
+var _utils = require("./utils");
 
-var _set_hours2 = _interopRequireDefault(_set_hours);
-
-var _get_day = require("date-fns/get_day");
-
-var _get_day2 = _interopRequireDefault(_get_day);
-
-var _format = require("date-fns/format");
-
-var _format2 = _interopRequireDefault(_format);
-
-var _is_within_range = require("date-fns/is_within_range");
-
-var _is_within_range2 = _interopRequireDefault(_is_within_range);
-
-var _is_future = require("date-fns/is_future");
-
-var _is_future2 = _interopRequireDefault(_is_future);
-
-var _add_days = require("date-fns/add_days");
-
-var _add_days2 = _interopRequireDefault(_add_days);
-
-var _is_equal = require("date-fns/is_equal");
-
-var _is_equal2 = _interopRequireDefault(_is_equal);
-
-var _is_before = require("date-fns/is_before");
-
-var _is_before2 = _interopRequireDefault(_is_before);
+var _utils2 = _interopRequireDefault(_utils);
 
 var _lodash = require("lodash");
 
@@ -46,7 +18,7 @@ function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { de
 
 function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
 
-var weekdays = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
+var weekdays = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"];
 
 var BusinessHours = function () {
   function BusinessHours() {
@@ -66,6 +38,11 @@ var BusinessHours = function () {
       if (isNaN(hour)) return false;
       return true;
     }
+  }, {
+    key: "_getISOWeekDayName",
+    value: function _getISOWeekDayName(isoDay) {
+      return weekdays[isoDay - 1];
+    }
   }, {
     key: "init",
     value: function init(hours) {
@@ -76,17 +53,17 @@ var BusinessHours = function () {
       }
 
       weekdays.forEach(function (day, index) {
-        if (!hours.hasOwnProperty(index.toString())) {
+        if (!hours.hasOwnProperty(day)) {
           throw new Error(day + " is missing from config");
         } else {
-          if (hours[index.toString()] !== "closed") {
-            if (!hours[index.toString()][0].hasOwnProperty("from")) {
+          if (hours[day] !== "closed") {
+            if (!hours[day][0].hasOwnProperty("from")) {
               console.error(day + " is missing 'from' in config");
-            } else if (!hours[index.toString()][0].hasOwnProperty("to")) {
+            } else if (!hours[day][0].hasOwnProperty("to")) {
               console.error(day + " is missing 'to' in config");
-            } else if (!_this._isHourValid(hours[index.toString()][0].from)) {
+            } else if (!_this._isHourValid(hours[day][0].from)) {
               console.error(day + "'s 'from' has not the right format. Should be ##:##");
-            } else if (!_this._isHourValid(hours[index.toString()][0].to)) {
+            } else if (!_this._isHourValid(hours[day][0].to)) {
               console.error(day + "'s 'to' has not the right format. Should be ##:##");
             }
           }
@@ -98,16 +75,19 @@ var BusinessHours = function () {
   }, {
     key: "isClosedNow",
     value: function isClosedNow() {
-      var now = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : new Date();
+      var now = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : _utils2.default.now(this.hours.timeZone);
 
       return !this.isOpenNow(now);
     }
   }, {
     key: "isOpenNow",
     value: function isOpenNow() {
-      var now = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : new Date();
+      var now = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : _utils2.default.now(this.hours.timeZone);
 
-      var day = (0, _get_day2.default)(now);
+      var day = this._getISOWeekDayName(now.isoWeekday());
+      if (this.isOnHoliday(now)) {
+        return false;
+      }
       //  console.log("now: ", format(now, "DD/MM/YYYY HH:mm"));
       var isOpenNow = false;
       if (this.hours[day.toString()] === "closed") return isOpenNow;
@@ -118,9 +98,17 @@ var BusinessHours = function () {
         var fromMinutes = from.substr(3, 2);
         var toHours = to.substr(0, 2);
         var toMinutes = to.substr(3, 2);
-        var fromDate = (0, _set_hours2.default)((0, _set_minutes2.default)(now, fromMinutes), fromHours);
-        var toDate = (0, _set_hours2.default)((0, _set_minutes2.default)(now, toMinutes), toHours);
-        isOpenNow = (0, _is_within_range2.default)(now, fromDate, toDate);
+        var fromDate = now.clone();
+        fromDate.set({
+          hour: fromHours,
+          minute: fromMinutes
+        });
+        var toDate = now.clone();
+        toDate.set({
+          hour: toHours,
+          minute: toMinutes
+        });
+        isOpenNow = now.isBetween(fromDate, toDate);
 
         return isOpenNow;
       });
@@ -129,26 +117,28 @@ var BusinessHours = function () {
   }, {
     key: "willBeOpenOn",
     value: function willBeOpenOn(date) {
-      var day = (0, _get_day2.default)(date);
-      if ((0, _is_future2.default)(date) || (0, _is_equal2.default)(new Date(), date)) {
-        if (this.hours[day.toString()] !== "closed") {
+      var day = this._getISOWeekDayName(date.isoWeekday());
+      var now = _utils2.default.now(this.hours.timeZone);
+      if (now.isBefore(date) || now.isSame(date)) {
+        if (this.hours[day] !== "closed" && !this.isOnHoliday(date)) {
           return true;
         } else {
           return false;
         }
       }
+
       return false;
     }
   }, {
     key: "isOpenTomorrow",
     value: function isOpenTomorrow() {
-      var tomorrow = (0, _add_days2.default)(new Date(), 1);
+      var tomorrow = _utils2.default.now(this.hours.timeZone).add(1, "days");
       return this.willBeOpenOn(tomorrow);
     }
   }, {
     key: "isOpenAfterTomorrow",
     value: function isOpenAfterTomorrow() {
-      var afterTomorrow = (0, _add_days2.default)(new Date(), 2);
+      var afterTomorrow = _utils2.default.now(this.hours.timeZone).add(2, "days");
       return this.willBeOpenOn(afterTomorrow);
     }
   }, {
@@ -156,9 +146,10 @@ var BusinessHours = function () {
     value: function nextOpeningDate() {
       var includeToday = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : false;
 
-      var date = (0, _add_days2.default)(new Date(), 1);
-      if (includeToday) {
-        date = new Date();
+      var date = _utils2.default.now(this.hours.timeZone);
+
+      if (!includeToday) {
+        date.add(1, "days");
       }
 
       var nextOpeningDate = null;
@@ -166,10 +157,10 @@ var BusinessHours = function () {
         if (this.willBeOpenOn(date)) {
           nextOpeningDate = date;
         } else {
-          date = (0, _add_days2.default)(date, 1);
+          date.add(1, "days");
         }
       }
-      return nextOpeningDate;
+      return nextOpeningDate.hours(0).minutes(0).seconds(0);
     }
   }, {
     key: "nextOpeningHour",
@@ -183,18 +174,21 @@ var BusinessHours = function () {
   }, {
     key: "_nextOpeningHour",
     value: function _nextOpeningHour(nextOpeningDate) {
-      var day = (0, _get_day2.default)(nextOpeningDate);
+      var _this2 = this;
+
+      var day = this._getISOWeekDayName(nextOpeningDate.isoWeekday());
       var firstDate = null;
-      this.hours[day.toString()].some(function (fromTo, index) {
+      this.hours[day].some(function (fromTo, index) {
         var from = fromTo.from;
         var to = fromTo.to;
         var fromHours = from.substr(0, 2);
         var fromMinutes = from.substr(3, 2);
         var toHours = to.substr(0, 2);
         var toMinutes = to.substr(3, 2);
-        var fromDate = (0, _set_hours2.default)((0, _set_minutes2.default)(nextOpeningDate, fromMinutes), fromHours);
 
-        if ((0, _is_before2.default)(new Date(), fromDate)) {
+        var fromDate = nextOpeningDate.hours(fromHours).minutes(fromMinutes).seconds(0);
+
+        if (_utils2.default.now(_this2.hours.timeZone).isBefore(fromDate)) {
           firstDate = fromDate;
           return true;
         }
@@ -205,6 +199,49 @@ var BusinessHours = function () {
     //nextOpeningDateText
     //nextOpeningHourText
 
+  }, {
+    key: "isOnHoliday",
+    value: function isOnHoliday() {
+      var now = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : _utils2.default.now(this.hours.timeZone);
+      var callback = arguments[1];
+
+      if (_lodash2.default.isEmpty(this.hours)) {
+        throw new Error("Hours are not set. Check your init() function or configuration.");
+      }
+      if (_lodash2.default.isEmpty(this.hours.holidays)) {
+        this.hours.holidays = [];
+      }
+      for (var i = 0; i < this.hours.holidays.length; i++) {
+        if (this.hours.holidays[i].indexOf("-") > -1) {
+          var dates = this.hours.holidays[i].split("-");
+          var beginDate = (0, _momentTimezone2.default)(dates[0]);
+          var endDate = (0, _momentTimezone2.default)(dates[1]);
+          if (now.isBetween(beginDate, endDate)) {
+            typeof callback === "function" && callback();
+            return true;
+          }
+        } else {
+          var holidayDate = (0, _momentTimezone2.default)(this.hours.holidays[i]);
+          if (now.isSame(holidayDate, "day")) {
+            typeof callback === "function" && callback();
+            return true;
+          }
+        }
+      }
+      return false;
+    }
+  }, {
+    key: "isOnHolidayInDays",
+    value: function isOnHolidayInDays() {
+      var x = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 1;
+
+      if (!_lodash2.default.isInteger(x)) {
+        throw new Error("isOnHolidayInDays(:int) only accepts integers.");
+      }
+      var futureDate = _utils2.default.now(this.hours.timeZone).add(x, "days");
+
+      return this.isOnHoliday(futureDate);
+    }
   }]);
 
   return BusinessHours;
diff --git a/dist/utils/index.js b/dist/utils/index.js
new file mode 100644
index 0000000..63e808f
--- /dev/null
+++ b/dist/utils/index.js
@@ -0,0 +1,33 @@
+"use strict";
+
+var _momentTimezone = require("moment-timezone");
+
+var _momentTimezone2 = _interopRequireDefault(_momentTimezone);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+// hours and month start from 0
+// date starts at 1
+var utils = {
+  createDate: function createDate(year, month, date, hour, minute) {
+    var timeZone = arguments.length > 5 && arguments[5] !== undefined ? arguments[5] : "Europe/Amsterdam";
+
+    var newDate = _momentTimezone2.default.tz(timeZone);
+    newDate.set({
+      year: year,
+      month: month,
+      date: date,
+      hour: hour,
+      minute: minute
+    });
+
+    return newDate;
+  },
+  now: function now() {
+    var timeZone = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : "Europe/Amsterdam";
+
+    return _momentTimezone2.default.tz(timeZone);
+  }
+};
+
+module.exports = utils;
\ No newline at end of file
diff --git a/example/package.json b/example/package.json
index 4b68b5a..4f89d2c 100644
--- a/example/package.json
+++ b/example/package.json
@@ -6,10 +6,11 @@
     "react-scripts": "1.0.17"
   },
   "dependencies": {
-    "business-hours.js": "1.0.3",
+    "business-hours.js": "latest",
+    "moment-timezone": "0.5.14",
     "react": "16.1.0",
     "react-dom": "16.1.0",
-    "react-live-clock": "2.0.1"
+    "react-live-clock": "2.0.2"
   },
   "scripts": {
     "start": "react-scripts start",
diff --git a/example/src/App.css b/example/src/App.css
index c5c6e8a..b0514fa 100644
--- a/example/src/App.css
+++ b/example/src/App.css
@@ -9,7 +9,7 @@
 
 .App-header {
   background-color: #222;
-  height: 150px;
+  height: 200px;
   padding: 20px;
   color: white;
 }
@@ -23,6 +23,17 @@
 }
 
 @keyframes App-logo-spin {
-  from { transform: rotate(0deg); }
-  to { transform: rotate(360deg); }
+  from {
+    transform: rotate(0deg);
+  }
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+.closed {
+  color: red;
+}
+.open {
+  color: green;
 }
diff --git a/example/src/App.js b/example/src/App.js
index 541ad96..9342822 100644
--- a/example/src/App.js
+++ b/example/src/App.js
@@ -13,20 +13,36 @@ class App extends Component {
     return (
       <div className="App">
         <header className="App-header">
-          Now it is:{" "}
-          <Clock format={"HH:mm on dddd, MMMM Do YYYY"} ticking={true} />
+          <h1>business-hours.js Example</h1>
+          <h3>
+            {" "}
+            Browser timezone:{" "}
+            <Clock format={"HH:mm on dddd, MMMM Do YYYY z"} ticking={true} />
+          </h3>
+          <h3>
+            {" "}
+            Business timezone:{" "}
+            <Clock
+              format={"HH:mm on dddd, MMMM Do YYYY z"}
+              ticking={true}
+              timezone={hoursJson.timeZone}
+            />
+          </h3>
+
           <p className="App-intro">
-            Is open now? {businessHours.isOpenNow().toString()}
+            The business is currently:{" "}
+            {businessHours.isOpenNow() ? (
+              <span className="open">OPEN</span>
+            ) : (
+              <span className="open">CLOSED</span>
+            )}
           </p>
-          <p>Next opening hour: {businessHours.nextOpeningHour().toString()}</p>
           <p>
-            Is it open tomorrow? {businessHours.isOpenTomorrow().toString()}
+            Next opening hour:{" "}
+            {businessHours.nextOpeningHour().format("YYYY-MM-DD HH:mm z")}
           </p>
         </header>
-        <h1>business-hours.js Example</h1>
-        <p>
-          Sunday: <br />10:00-13:30 and 17:00-20:00 and 21:00-24:00
-        </p>
+        <h2>Defined business hours:</h2>
         <p>
           Monday: <br />10:00-13:30 and 18:00-22:00
         </p>
@@ -45,6 +61,9 @@ class App extends Component {
         <p>
           Satuday: <br />10:00-13:30 and 18:00-22:00
         </p>
+        <p>
+          Sunday: <br />10:00-13:30 and 17:00-20:00 and 21:00-24:00
+        </p>
       </div>
     );
   }
diff --git a/example/src/hours.json b/example/src/hours.json
index c0b4aa3..52cd942 100644
--- a/example/src/hours.json
+++ b/example/src/hours.json
@@ -1,19 +1,16 @@
 {
-  "0": [
+  "Monday": [
     {
       "from": "10:00",
       "to": "13:30"
     },
     {
-      "from": "17:00",
-      "to": "20:00"
-    },
-    {
-      "from": "21:00",
-      "to": "24:00"
+      "from": "18:00",
+      "to": "22:00"
     }
   ],
-  "1": [
+  "Tuesday": "closed",
+  "Wednesday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -23,8 +20,7 @@
       "to": "22:00"
     }
   ],
-  "2": "closed",
-  "3": [
+  "Thursday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -34,7 +30,7 @@
       "to": "22:00"
     }
   ],
-  "4": [
+  "Friday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -44,7 +40,7 @@
       "to": "22:00"
     }
   ],
-  "5": [
+  "Saturday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -54,14 +50,20 @@
       "to": "22:00"
     }
   ],
-  "6": [
+  "Sunday": [
     {
       "from": "10:00",
       "to": "13:30"
     },
     {
-      "from": "18:00",
-      "to": "22:00"
+      "from": "17:00",
+      "to": "20:00"
+    },
+    {
+      "from": "21:00",
+      "to": "24:00"
     }
-  ]
+  ],
+  "holidays": ["2017/12/11", "2017/12/23-2018/01/02"],
+  "timeZone": "Europe/Amsterdam"
 }
diff --git a/example/yarn.lock b/example/yarn.lock
index a8481ea..e61712d 100644
--- a/example/yarn.lock
+++ b/example/yarn.lock
@@ -4163,6 +4163,12 @@ moment-timezone@0.5.13:
   dependencies:
     moment ">= 2.9.0"
 
+moment-timezone@0.5.14:
+  version "0.5.14"
+  resolved "https://registry.yarnpkg.com/moment-timezone/-/moment-timezone-0.5.14.tgz#4eb38ff9538b80108ba467a458f3ed4268ccfcb1"
+  dependencies:
+    moment ">= 2.9.0"
+
 moment@2.18.1:
   version "2.18.1"
   resolved "https://registry.yarnpkg.com/moment/-/moment-2.18.1.tgz#c36193dd3ce1c2eed2adb7c802dbbc77a81b1c0f"
@@ -5155,9 +5161,9 @@ react-error-overlay@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/react-error-overlay/-/react-error-overlay-3.0.0.tgz#c2bc8f4d91f1375b3dad6d75265d51cd5eeaf655"
 
-react-live-clock@2.0.1:
-  version "2.0.1"
-  resolved "https://registry.yarnpkg.com/react-live-clock/-/react-live-clock-2.0.1.tgz#f50c47059b6ab7f66979430803695a3bf2946174"
+react-live-clock@2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/react-live-clock/-/react-live-clock-2.0.2.tgz#c9e7a75b525db9c897f9a7b7f266cd3d671acc5d"
   dependencies:
     moment "2.18.1"
     moment-timezone "0.5.13"
diff --git a/package.json b/package.json
index 48a717c..184c8fd 100644
--- a/package.json
+++ b/package.json
@@ -6,19 +6,19 @@
   "scripts": {
     "commit": "git-cz",
     "precommit": "npm run build && npm run test:single",
-    "report-coverage":
-      "nyc report --reporter=lcov | codecov -t c1cea4d6-9aec-445c-8179-bc5543358876",
+    "report-coverage": "nyc report --reporter=lcov | codecov -t c1cea4d6-9aec-445c-8179-bc5543358876",
     "prebuild": "rimraf dist",
-    "build-with-files":
-      "npm run prebuild && babel --copy-files --out-dir dist --ignore *.test.js src",
+    "build-with-files": "npm run prebuild && babel --copy-files --out-dir dist --ignore *.test.js src",
     "build": "npm run prebuild && babel --out-dir dist --ignore *.test.js src",
     "test": "mocha --compilers js:babel-register src/index.test.js -w",
     "test:single": "nyc mocha --compilers js:babel-register src/index.test.js",
-    "semantic-release":
-      "semantic-release pre && npm publish && semantic-release post"
+    "semantic-release": "semantic-release pre && npm publish && semantic-release post"
   },
   "babel": {
-    "presets": ["es2015", "stage-2"]
+    "presets": [
+      "es2015",
+      "stage-2"
+    ]
   },
   "repository": {
     "type": "git",
@@ -55,8 +55,8 @@
     }
   },
   "dependencies": {
-    "date-fns": "1.28.5",
     "lodash": "4.17.4",
-    "mockdate": "2.0.2"
+    "mockdate": "2.0.2",
+    "moment-timezone": "0.5.14"
   }
 }
diff --git a/src/hours.json b/src/hours.json
index c0b4aa3..52cd942 100644
--- a/src/hours.json
+++ b/src/hours.json
@@ -1,19 +1,16 @@
 {
-  "0": [
+  "Monday": [
     {
       "from": "10:00",
       "to": "13:30"
     },
     {
-      "from": "17:00",
-      "to": "20:00"
-    },
-    {
-      "from": "21:00",
-      "to": "24:00"
+      "from": "18:00",
+      "to": "22:00"
     }
   ],
-  "1": [
+  "Tuesday": "closed",
+  "Wednesday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -23,8 +20,7 @@
       "to": "22:00"
     }
   ],
-  "2": "closed",
-  "3": [
+  "Thursday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -34,7 +30,7 @@
       "to": "22:00"
     }
   ],
-  "4": [
+  "Friday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -44,7 +40,7 @@
       "to": "22:00"
     }
   ],
-  "5": [
+  "Saturday": [
     {
       "from": "10:00",
       "to": "13:30"
@@ -54,14 +50,20 @@
       "to": "22:00"
     }
   ],
-  "6": [
+  "Sunday": [
     {
       "from": "10:00",
       "to": "13:30"
     },
     {
-      "from": "18:00",
-      "to": "22:00"
+      "from": "17:00",
+      "to": "20:00"
+    },
+    {
+      "from": "21:00",
+      "to": "24:00"
     }
-  ]
+  ],
+  "holidays": ["2017/12/11", "2017/12/23-2018/01/02"],
+  "timeZone": "Europe/Amsterdam"
 }
diff --git a/src/hoursMissingHolidays.json b/src/hoursMissingHolidays.json
new file mode 100644
index 0000000..9668327
--- /dev/null
+++ b/src/hoursMissingHolidays.json
@@ -0,0 +1,67 @@
+{
+  "Monday": [
+    {
+      "from": "10:00",
+      "to": "13:30"
+    },
+    {
+      "from": "18:00",
+      "to": "22:00"
+    }
+  ],
+  "Tuesday": "closed",
+  "Wednesday": [
+    {
+      "from": "10:00",
+      "to": "13:30"
+    },
+    {
+      "from": "18:00",
+      "to": "22:00"
+    }
+  ],
+  "Thursday": [
+    {
+      "from": "10:00",
+      "to": "13:30"
+    },
+    {
+      "from": "18:00",
+      "to": "22:00"
+    }
+  ],
+  "Friday": [
+    {
+      "from": "10:00",
+      "to": "13:30"
+    },
+    {
+      "from": "18:00",
+      "to": "22:00"
+    }
+  ],
+  "Saturday": [
+    {
+      "from": "10:00",
+      "to": "13:30"
+    },
+    {
+      "from": "18:00",
+      "to": "22:00"
+    }
+  ],
+  "Sunday": [
+    {
+      "from": "10:00",
+      "to": "13:30"
+    },
+    {
+      "from": "17:00",
+      "to": "20:00"
+    },
+    {
+      "from": "21:00",
+      "to": "24:00"
+    }
+  ]
+}
diff --git a/src/index.js b/src/index.js
index a029c73..3abb217 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,21 +1,14 @@
-import setMinutes from "date-fns/set_minutes";
-import setHours from "date-fns/set_hours";
-import getDay from "date-fns/get_day";
-import format from "date-fns/format";
-import isWithinRange from "date-fns/is_within_range";
-import isFuture from "date-fns/is_future";
-import addDays from "date-fns/add_days";
-import isEqual from "date-fns/is_equal";
-import isBefore from "date-fns/is_before";
+import moment from "moment-timezone";
+import utils from "./utils";
 import _ from "lodash";
 const weekdays = [
-  "Sunday",
   "Monday",
   "Tuesday",
   "Wednesday",
   "Thursday",
   "Friday",
-  "Saturday"
+  "Saturday",
+  "Sunday"
 ];
 
 class BusinessHours {
@@ -32,6 +25,9 @@ class BusinessHours {
     if (isNaN(hour)) return false;
     return true;
   }
+  _getISOWeekDayName(isoDay) {
+    return weekdays[isoDay - 1];
+  }
 
   init(hours) {
     if (_.isEmpty(hours)) {
@@ -39,19 +35,19 @@ class BusinessHours {
     }
 
     weekdays.forEach((day, index) => {
-      if (!hours.hasOwnProperty(index.toString())) {
+      if (!hours.hasOwnProperty(day)) {
         throw new Error(day + " is missing from config");
       } else {
-        if (hours[index.toString()] !== "closed") {
-          if (!hours[index.toString()][0].hasOwnProperty("from")) {
+        if (hours[day] !== "closed") {
+          if (!hours[day][0].hasOwnProperty("from")) {
             console.error(day + " is missing 'from' in config");
-          } else if (!hours[index.toString()][0].hasOwnProperty("to")) {
+          } else if (!hours[day][0].hasOwnProperty("to")) {
             console.error(day + " is missing 'to' in config");
-          } else if (!this._isHourValid(hours[index.toString()][0].from)) {
+          } else if (!this._isHourValid(hours[day][0].from)) {
             console.error(
               day + "'s 'from' has not the right format. Should be ##:##"
             );
-          } else if (!this._isHourValid(hours[index.toString()][0].to)) {
+          } else if (!this._isHourValid(hours[day][0].to)) {
             console.error(
               day + "'s 'to' has not the right format. Should be ##:##"
             );
@@ -63,12 +59,15 @@ class BusinessHours {
     this.hours = hours;
   }
 
-  isClosedNow(now = new Date()) {
+  isClosedNow(now = utils.now(this.hours.timeZone)) {
     return !this.isOpenNow(now);
   }
 
-  isOpenNow(now = new Date()) {
-    const day = getDay(now);
+  isOpenNow(now = utils.now(this.hours.timeZone)) {
+    const day = this._getISOWeekDayName(now.isoWeekday());
+    if (this.isOnHoliday(now)) {
+      return false;
+    }
     //  console.log("now: ", format(now, "DD/MM/YYYY HH:mm"));
     let isOpenNow = false;
     if (this.hours[day.toString()] === "closed") return isOpenNow;
@@ -79,9 +78,17 @@ class BusinessHours {
       const fromMinutes = from.substr(3, 2);
       const toHours = to.substr(0, 2);
       const toMinutes = to.substr(3, 2);
-      const fromDate = setHours(setMinutes(now, fromMinutes), fromHours);
-      const toDate = setHours(setMinutes(now, toMinutes), toHours);
-      isOpenNow = isWithinRange(now, fromDate, toDate);
+      let fromDate = now.clone();
+      fromDate.set({
+        hour: fromHours,
+        minute: fromMinutes
+      });
+      let toDate = now.clone();
+      toDate.set({
+        hour: toHours,
+        minute: toMinutes
+      });
+      isOpenNow = now.isBetween(fromDate, toDate);
 
       return isOpenNow;
     });
@@ -89,29 +96,34 @@ class BusinessHours {
   }
 
   willBeOpenOn(date) {
-    const day = getDay(date);
-    if (isFuture(date) || isEqual(new Date(), date)) {
-      if (this.hours[day.toString()] !== "closed") {
+    const day = this._getISOWeekDayName(date.isoWeekday());
+    const now = utils.now(this.hours.timeZone);
+    if (now.isBefore(date) || now.isSame(date)) {
+      if (this.hours[day] !== "closed" && !this.isOnHoliday(date)) {
         return true;
       } else {
         return false;
       }
     }
+
     return false;
   }
+
   isOpenTomorrow() {
-    const tomorrow = addDays(new Date(), 1);
+    const tomorrow = utils.now(this.hours.timeZone).add(1, "days");
     return this.willBeOpenOn(tomorrow);
   }
+
   isOpenAfterTomorrow() {
-    const afterTomorrow = addDays(new Date(), 2);
+    const afterTomorrow = utils.now(this.hours.timeZone).add(2, "days");
     return this.willBeOpenOn(afterTomorrow);
   }
 
   nextOpeningDate(includeToday = false) {
-    let date = addDays(new Date(), 1);
-    if (includeToday) {
-      date = new Date();
+    let date = utils.now(this.hours.timeZone);
+
+    if (!includeToday) {
+      date.add(1, "days");
     }
 
     let nextOpeningDate = null;
@@ -119,10 +131,13 @@ class BusinessHours {
       if (this.willBeOpenOn(date)) {
         nextOpeningDate = date;
       } else {
-        date = addDays(date, 1);
+        date.add(1, "days");
       }
     }
-    return nextOpeningDate;
+    return nextOpeningDate
+      .hours(0)
+      .minutes(0)
+      .seconds(0);
   }
 
   nextOpeningHour() {
@@ -133,21 +148,22 @@ class BusinessHours {
     return nextOpeningHour;
   }
   _nextOpeningHour(nextOpeningDate) {
-    const day = getDay(nextOpeningDate);
+    const day = this._getISOWeekDayName(nextOpeningDate.isoWeekday());
     let firstDate = null;
-    this.hours[day.toString()].some((fromTo, index) => {
+    this.hours[day].some((fromTo, index) => {
       const from = fromTo.from;
       const to = fromTo.to;
       const fromHours = from.substr(0, 2);
       const fromMinutes = from.substr(3, 2);
       const toHours = to.substr(0, 2);
       const toMinutes = to.substr(3, 2);
-      const fromDate = setHours(
-        setMinutes(nextOpeningDate, fromMinutes),
-        fromHours
-      );
 
-      if (isBefore(new Date(), fromDate)) {
+      let fromDate = nextOpeningDate
+        .hours(fromHours)
+        .minutes(fromMinutes)
+        .seconds(0);
+
+      if (utils.now(this.hours.timeZone).isBefore(fromDate)) {
         firstDate = fromDate;
         return true;
       }
@@ -157,6 +173,44 @@ class BusinessHours {
   }
   //nextOpeningDateText
   //nextOpeningHourText
+
+  isOnHoliday(now = utils.now(this.hours.timeZone), callback) {
+    if (_.isEmpty(this.hours)) {
+      throw new Error(
+        "Hours are not set. Check your init() function or configuration."
+      );
+    }
+    if (_.isEmpty(this.hours.holidays)) {
+      this.hours.holidays = [];
+    }
+    for (let i = 0; i < this.hours.holidays.length; i++) {
+      if (this.hours.holidays[i].indexOf("-") > -1) {
+        let dates = this.hours.holidays[i].split("-");
+        let beginDate = moment(dates[0]);
+        let endDate = moment(dates[1]);
+        if (now.isBetween(beginDate, endDate)) {
+          typeof callback === "function" && callback();
+          return true;
+        }
+      } else {
+        let holidayDate = moment(this.hours.holidays[i]);
+        if (now.isSame(holidayDate, "day")) {
+          typeof callback === "function" && callback();
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  isOnHolidayInDays(x = 1) {
+    if (!_.isInteger(x)) {
+      throw new Error("isOnHolidayInDays(:int) only accepts integers.");
+    }
+    let futureDate = utils.now(this.hours.timeZone).add(x, "days");
+
+    return this.isOnHoliday(futureDate);
+  }
 }
 
 module.exports = new BusinessHours();
diff --git a/src/index.test.js b/src/index.test.js
index 85ded12..4ecc3ad 100644
--- a/src/index.test.js
+++ b/src/index.test.js
@@ -2,36 +2,73 @@ var expect = require("chai").expect;
 var bh = require("./index.js");
 var hoursJson = require("./hours.json");
 var hoursJson2 = require("./hours2.json");
+var hoursJsonMissingHolidays = require("./hoursMissingHolidays.json");
+var utils = require("./utils/index.js");
 var MockDate = require("mockdate");
-import format from "date-fns/format";
 
-bh.init(hoursJson);
+const TIMEZONE = "Europe/Luxembourg";
 
 describe("business-hours-js", function() {
-  after(function() {
+  beforeEach(function() {
+    bh.init(hoursJson);
+  });
+  afterEach(function() {
     MockDate.reset();
   });
+
   describe("isOpenNow", function() {
     it("outside business hours, should equal false", function() {
-      expect(bh.isOpenNow(new Date(2017, 9, 1, 16, 0))).to.equal(false);
+      expect(
+        bh.isOpenNow(utils.createDate(2017, 9, 1, 14, 0, TIMEZONE))
+      ).to.equal(false);
     });
     it("inside business hours, should equal true", function() {
-      expect(bh.isOpenNow(new Date(2017, 9, 1, 18, 0))).to.equal(true);
+      expect(
+        bh.isOpenNow(utils.createDate(2017, 9, 1, 18, 0, TIMEZONE))
+      ).to.equal(true);
+    });
+    it("closed day, should equal false", function() {
+      expect(
+        bh.isOpenNow(utils.createDate(2017, 9, 3, 18, 0, TIMEZONE))
+      ).to.equal(false);
+    });
+    it("on holiday day, should equal false", function() {
+      expect(
+        bh.isOpenNow(utils.createDate(2017, 11, 9, 0, 0, TIMEZONE))
+      ).to.equal(false);
     });
-    it("cloded day, should equal false", function() {
-      expect(bh.isOpenNow(new Date(2017, 9, 3, 18, 0))).to.equal(false);
+    it("on holiday day (range), should equal false", function() {
+      expect(
+        bh.isOpenNow(utils.createDate(2017, 11, 24, 0, 0, TIMEZONE))
+      ).to.equal(false);
     });
   });
 
   describe("isClosedNow", function() {
     it("outside business hours, should equal true", function() {
-      expect(bh.isClosedNow(new Date(2017, 9, 1, 16, 0))).to.equal(true);
+      expect(
+        bh.isClosedNow(utils.createDate(2017, 9, 1, 14, 0, TIMEZONE))
+      ).to.equal(true);
     });
     it("inside business hours, should equal false", function() {
-      expect(bh.isClosedNow(new Date(2017, 9, 1, 18, 0))).to.equal(false);
+      expect(
+        bh.isClosedNow(utils.createDate(2017, 9, 1, 18, 0, TIMEZONE))
+      ).to.equal(false);
     });
-    it("cloded day, should equal true", function() {
-      expect(bh.isClosedNow(new Date(2017, 9, 3, 18, 0))).to.equal(true);
+    it("closed day, should equal true", function() {
+      expect(
+        bh.isClosedNow(utils.createDate(2017, 9, 3, 18, 0, TIMEZONE))
+      ).to.equal(true);
+    });
+    it("on holiday day, should equal true", function() {
+      expect(
+        bh.isClosedNow(utils.createDate(2017, 11, 9, 0, 0, TIMEZONE))
+      ).to.equal(true);
+    });
+    it("on holiday day (range), should equal true", function() {
+      expect(
+        bh.isClosedNow(utils.createDate(2017, 11, 24, 0, 0, TIMEZONE))
+      ).to.equal(true);
     });
   });
 
@@ -58,13 +95,19 @@ describe("business-hours-js", function() {
 
   describe("willBeOpenOn", function() {
     it("with future date, should be true", function() {
-      expect(bh.willBeOpenOn(new Date(2019, 9, 3))).to.equal(true);
+      expect(
+        bh.willBeOpenOn(utils.createDate(2018, 0, 3, 0, 0, TIMEZONE))
+      ).to.equal(true);
     });
     it("with future date, on closed day, should be false", function() {
-      expect(bh.willBeOpenOn(new Date(2019, 9, 1))).to.equal(false);
+      expect(
+        bh.willBeOpenOn(utils.createDate(2019, 0, 1, 0, 0, TIMEZONE))
+      ).to.equal(false);
     });
     it("with past date, should be false", function() {
-      expect(bh.willBeOpenOn(new Date(2015, 9, 1))).to.equal(false);
+      expect(
+        bh.willBeOpenOn(utils.createDate(2015, 0, 1, 0, 0, TIMEZONE))
+      ).to.equal(false);
     });
   });
   describe("isOpenTomorrow", function() {
@@ -96,74 +139,140 @@ describe("business-hours-js", function() {
   describe("nextOpeningDate", function() {
     it("monday 2/10/2017, should return 4/10/2017", function() {
       MockDate.set("10/2/2017");
-      var expectedDate = new Date(2017, 9, 4, 0, 0);
-      expect(bh.nextOpeningDate().getTime()).to.equal(expectedDate.getTime());
+      var expectedDate = utils.createDate(2017, 9, 4, 0, 0, TIMEZONE);
+      expect(bh.nextOpeningDate().isSame(expectedDate, "day")).to.equal(true);
       MockDate.reset();
     });
     it("tuesday 3/10/2017, should return 4/10/2017", function() {
       MockDate.set("10/3/2017");
-      var expectedDate = new Date(2017, 9, 4, 0, 0);
-      expect(bh.nextOpeningDate().getTime()).to.equal(expectedDate.getTime());
+      var expectedDate = utils.createDate(2017, 9, 4, 0, 0, TIMEZONE);
+      expect(bh.nextOpeningDate().isSame(expectedDate, "day")).to.equal(true);
       MockDate.reset();
     });
     it("wednesday 4/10/2017, should return 5/10/2017", function() {
       MockDate.set("10/4/2017");
-      var expectedDate = new Date(2017, 9, 5, 0, 0);
-      expect(bh.nextOpeningDate().getTime()).to.equal(expectedDate.getTime());
+      var expectedDate = utils.createDate(2017, 9, 5, 0, 0, TIMEZONE);
+      expect(bh.nextOpeningDate().isSame(expectedDate, "day")).to.equal(true);
       MockDate.reset();
     });
     it("sunday 8/10/2017, should return monday 9/10/2017", function() {
       MockDate.set("10/8/2017");
-      var expectedDate = new Date(2017, 9, 9, 0, 0);
-      expect(bh.nextOpeningDate().getTime()).to.equal(expectedDate.getTime());
+      var expectedDate = utils.createDate(2017, 9, 9, 0, 0, TIMEZONE);
+      expect(bh.nextOpeningDate().isSame(expectedDate, "day")).to.equal(true);
       MockDate.reset();
     });
     it("monday 2/10/2017, should return monday 2/10/2017", function() {
       MockDate.set("10/2/2017");
-      var expectedDate = new Date(2017, 9, 2, 0, 0);
-      expect(bh.nextOpeningDate(true).getTime()).to.equal(
-        expectedDate.getTime()
+      var expectedDate = utils.createDate(2017, 9, 2, 0, 0, TIMEZONE);
+      expect(bh.nextOpeningDate(true).isSame(expectedDate, "day")).to.equal(
+        true
       );
       MockDate.reset();
     });
   });
   describe("nextOpeningHour", function() {
     it("monday 2/10/2017 6:00, should return 2/10/2017 10:00", function() {
-      MockDate.set(new Date(2017, 9, 2, 6, 0));
-      var expectedDate = new Date(2017, 9, 2, 10, 0);
-      expect(bh.nextOpeningHour().getTime()).to.equal(expectedDate.getTime());
+      MockDate.set(utils.createDate(2017, 9, 2, 6, 0, TIMEZONE));
+      var expectedDate = utils.createDate(2017, 9, 2, 10, 0);
+
+      expect(bh.nextOpeningHour().isSame(expectedDate, "minute")).to.equal(
+        true
+      );
       MockDate.reset();
     });
     it("monday 2/10/2017 16:00, should return 2/10/2017 18:00", function() {
-      MockDate.set(new Date(2017, 9, 2, 16, 0));
-      var expectedDate = new Date(2017, 9, 2, 18, 0);
-      expect(bh.nextOpeningHour().getTime()).to.equal(expectedDate.getTime());
+      MockDate.set(utils.createDate(2017, 9, 2, 16, 0, TIMEZONE));
+      var expectedDate = utils.createDate(2017, 9, 2, 18, 0, TIMEZONE);
+      expect(bh.nextOpeningHour().isSame(expectedDate, "minute")).to.equal(
+        true
+      );
       MockDate.reset();
     });
     it("sunday 1/10/2017 20:30, should return 1/10/2017 21:00", function() {
-      MockDate.set(new Date(2017, 9, 1, 20, 30));
-      var expectedDate = new Date(2017, 9, 1, 21, 0);
-      expect(bh.nextOpeningHour().getTime()).to.equal(expectedDate.getTime());
+      MockDate.set(utils.createDate(2017, 9, 1, 20, 30, TIMEZONE));
+      var expectedDate = utils.createDate(2017, 9, 1, 21, 0, TIMEZONE);
+      expect(bh.nextOpeningHour().isSame(expectedDate, "minute")).to.equal(
+        true
+      );
       MockDate.reset();
     });
     it("sunday 1/10/2017 21:30, should return 2/10/2017 10:00", function() {
-      MockDate.set(new Date(2017, 9, 1, 21, 30));
-      var expectedDate = new Date(2017, 9, 2, 10, 0);
-      expect(bh.nextOpeningHour().getTime()).to.equal(expectedDate.getTime());
+      MockDate.set(utils.createDate(2017, 9, 1, 21, 30, TIMEZONE));
+      var expectedDate = utils.createDate(2017, 9, 2, 10, 0, TIMEZONE);
+      expect(bh.nextOpeningHour().isSame(expectedDate, "minute")).to.equal(
+        true
+      );
       MockDate.reset();
     });
     it("tuesday(closed) 3/10/2017 18:30, should return 4/10/2017 10:00", function() {
-      MockDate.set(new Date(2017, 9, 3, 18, 30));
-      var expectedDate = new Date(2017, 9, 4, 10, 0);
-      expect(bh.nextOpeningHour().getTime()).to.equal(expectedDate.getTime());
+      MockDate.set(utils.createDate(2017, 9, 3, 18, 30, TIMEZONE));
+      var expectedDate = utils.createDate(2017, 9, 4, 10, 0, TIMEZONE);
+      expect(bh.nextOpeningHour().isSame(expectedDate, "minute")).to.equal(
+        true
+      );
       MockDate.reset();
     });
   });
+  describe("isOnHoliday", function() {
+    it("on holiday 2017/12/11", function() {
+      MockDate.set(utils.createDate(2017, 11, 11, 0, 0, TIMEZONE));
+      expect(bh.isOnHoliday()).to.equal(true);
+    });
+    it("after a holiday 2017/12/12", function() {
+      MockDate.set(utils.createDate(2017, 11, 12, 0, 0, TIMEZONE));
+      expect(bh.isOnHoliday()).to.equal(false);
+    });
+    it("before a holiday 2017/12/9", function() {
+      MockDate.set(utils.createDate(2017, 11, 9, 0, 0, TIMEZONE));
+      expect(bh.isOnHoliday()).to.equal(false);
+    });
+    it("in range 2017/12/24", function() {
+      MockDate.set(utils.createDate(2017, 11, 24, 0, 0, TIMEZONE));
+      expect(bh.isOnHoliday()).to.equal(true);
+    });
+    it("within range, with year change 2018/01/01", function() {
+      MockDate.set(utils.createDate(2018, 0, 1, 0, 0, TIMEZONE));
+      expect(bh.isOnHoliday()).to.equal(true);
+    });
+    it("outside range, with year change 2018/01/04", function() {
+      MockDate.set(utils.createDate(2018, 0, 4, 0, 0, TIMEZONE));
+      expect(bh.isOnHoliday()).to.equal(false);
+    });
+    it("missing holidays in config", function() {
+      bh.init(hoursJsonMissingHolidays);
+      expect(bh.isOnHoliday()).to.equal(false);
+    });
+  });
+  describe("isOnHolidayInDays", function() {
+    it("on holiday 3 days from 2017/12/08", function() {
+      MockDate.set(utils.createDate(2017, 11, 8, 0, 0, TIMEZONE));
+      expect(bh.isOnHolidayInDays(3)).to.equal(true);
+    });
+    it('Nan param "3 days"', function() {
+      expect(bh.isOnHolidayInDays.bind(bh, "3 days")).to.throw(
+        "isOnHolidayInDays(:int) only accepts integers."
+      );
+    });
+    it('NaN param "3"', function() {
+      expect(bh.isOnHolidayInDays.bind(bh, "3")).to.throw(
+        "isOnHolidayInDays(:int) only accepts integers."
+      );
+    });
+    it('NaN param "undefined", x defaults to 1', function() {
+      MockDate.set(utils.createDate(2017, 11, 8, 0, 0, TIMEZONE));
+      expect(bh.isOnHolidayInDays(undefined)).to.equal(false);
+    });
+    it('NaN param ""', function() {
+      expect(bh.isOnHolidayInDays.bind(bh, "")).to.throw(
+        "isOnHolidayInDays(:int) only accepts integers."
+      );
+    });
+  });
   //MockDate.set('1/1/2000');
   describe("init", function() {
-    it("missing sunday", function() {
+    it("missing monday", function() {
       expect(bh.init.bind(bh, hoursJson2)).to.throw(
-        "Sunday is missing from config"
+        "Monday is missing from config"
       );
     });
     it("missing config, empty object", function() {
@@ -183,7 +292,7 @@ describe("business-hours-js", function() {
     });
     it("missing config, {'a':'test'} ", function() {
       expect(bh.init.bind(bh, { a: "test" })).to.throw(
-        "Sunday is missing from config"
+        "Monday is missing from config"
       );
     });
   });
diff --git a/src/utils/index.js b/src/utils/index.js
new file mode 100644
index 0000000..8e3abee
--- /dev/null
+++ b/src/utils/index.js
@@ -0,0 +1,24 @@
+import moment from "moment-timezone";
+
+// hours and month start from 0
+// date starts at 1
+var utils = {
+  createDate(year, month, date, hour, minute, timeZone = "Europe/Amsterdam") {
+    let newDate = moment.tz(timeZone);
+    newDate.set({
+      year: year,
+      month: month,
+      date: date,
+      hour: hour,
+      minute: minute
+    });
+
+    return newDate;
+  },
+
+  now(timeZone = "Europe/Amsterdam") {
+    return moment.tz(timeZone);
+  }
+};
+
+module.exports = utils;