change DateToDay method to DateToDayCount method

Conversions/DateToDayCount.js

@@ -0,0 +1,51 @@
+/*
+DateToDayCount Method
+---------------------
+The DateToDayCount method takes a string date and tells
+how many days have passed from that date to the current date.
+
+Problem source and Explanation :
+    1) http://wiki.hotdocs.com/index.php?title=Determine_Number_of_Days_Between_Two_Dates
+    2) https://wiki.scn.sap.com/wiki/display/Snippets/calculate+no+of+working+days+between+two+dates
+*/
+
+const monthsNameList = { // create a monthsNameList for easy to use.
+  1: 'January',
+  2: 'February',
+  3: 'March',
+  4: 'April',
+  5: 'May',
+  6: 'June',
+  7: 'July',
+  8: 'August',
+  9: 'September',
+  10: 'October',
+  11: 'November',
+  12: 'December'
+}
+
+const DateToDayCount = (date) => {
+  // firstly, check that input is a string or not.
+  if (typeof date !== 'string') {
+    return new TypeError('Argument is not a string.')
+  }
+  // extarct the date
+  const [day, month, year] = date.split('/').map((x) => Number(x))
+  // check the data are valid or not.
+  if (day > 31 || month > 12) {
+    return new TypeError('Date is not valid.')
+  }
+  // create a base date for finding the actuale date.
+  const baseDate = `${monthsNameList[month]} ${day}, ${year} 24:00:00`
+  // use the Date class and make an object use of the base date.
+  const inputDate = new Date(baseDate)
+  // get the current date.
+  const currentDate = new Date()
+  // make some celculation for retrive the result.
+  const diffTime = Math.abs(currentDate - inputDate)
+  // convert time to day count.
+  const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24))
+  return diffDays
+}
+
+module.exports = DateToDayCount