update readme

README.md

@@ -1,3 +1,53 @@
-# calendarJS
+# CalendarJS
 
 Simple calendar grid generator for NodeJS
+
+## Install
+
+With NPM
+
+```npm install --save @enigmaoffline/calendarjs```
+
+## Usage
+
+```js
+const Calendar = require('@enigmaoffline/calendarjs');
+
+let cl = new Calendar(2020, 12);
+
+console.log(cl.getGrid());
+/* =>
+[ [ '29-11-2020', '30-11-2020', '01-12-2020', '02-12-2020', '03-12-2020', '04-12-2020', '05-12-2020' ],
+  [ '06-12-2020', '07-12-2020', '08-12-2020', '09-12-2020', '10-12-2020', '11-12-2020', '12-12-2020' ],
+  [ '13-12-2020', '14-12-2020', '15-12-2020', '16-12-2020', '17-12-2020', '18-12-2020', '19-12-2020' ],
+  [ '20-12-2020', '21-12-2020', '22-12-2020', '23-12-2020', '24-12-2020', '25-12-2020', '26-12-2020' ],
+  [ '27-12-2020', '28-12-2020', '29-12-2020', '30-12-2020', '31-12-2020', '01-01-2021', '02-01-2021' ] ]
+*/
+
+console.log(cl.isLeapYear());   // => true
+
+cl.nextMonth();
+
+console.log(cl.getGrid());
+/* =>
+[ [ '27-12-2020', '28-12-2020', '29-12-2020', '30-12-2020', '31-12-2020', '01-01-2021', '02-01-2021' ],
+  [ '03-01-2021', '04-01-2021', '05-01-2021', '06-01-2021', '07-01-2021', '08-01-2021', '09-01-2021' ],
+  [ '10-01-2021', '11-01-2021', '12-01-2021', '13-01-2021', '14-01-2021', '15-01-2021', '16-01-2021' ],
+  [ '17-01-2021', '18-01-2021', '19-01-2021', '20-01-2021', '21-01-2021', '22-01-2021', '23-01-2021' ],
+  [ '24-01-2021', '25-01-2021', '26-01-2021', '27-01-2021', '28-01-2021', '29-01-2021', '30-01-2021' ],
+  [ '31-01-2021', '01-02-2021', '02-02-2021', '03-02-2021', '04-02-2021', '05-02-2021', '06-02-2021' ] ]
+*/
+```
+
+### Static Usage
+
+```js
+const Calendar = require('@enigmaoffline/calendarjs');
+
+console.log(Calendar.getDateNum(2020, 2));  // => 29
+console.log(Calendar.getDateNum(2020, 3));  // => 31
+
+console.log(Calendar.getNextMonth(2021, 12));   // => { month: 1, year: 2022 }
+```
+
+<a href="https://github.com/lochungtin/calendarJS/blob/master/LICENSE">LICENSE - MIT - Lo Chung Tin</a>