Migrate differenceInCalendarMonths function to TS (#2419)

src/differenceInCalendarMonths/index.js → src/differenceInCalendarMonths/index.ts

@@ -27,16 +27,16 @@ import requiredArgs from '../_lib/requiredArgs/index'
  * //=> 8
  */
 export default function differenceInCalendarMonths(
-  dirtyDateLeft,
-  dirtyDateRight
-) {
+  dirtyDateLeft: Date | number,
+  dirtyDateRight: Date | number
+): number {
   requiredArgs(2, arguments)
 
-  var dateLeft = toDate(dirtyDateLeft)
-  var dateRight = toDate(dirtyDateRight)
+  const dateLeft = toDate(dirtyDateLeft)
+  const dateRight = toDate(dirtyDateRight)
 
-  var yearDiff = dateLeft.getFullYear() - dateRight.getFullYear()
-  var monthDiff = dateLeft.getMonth() - dateRight.getMonth()
+  const yearDiff = dateLeft.getFullYear() - dateRight.getFullYear()
+  const monthDiff = dateLeft.getMonth() - dateRight.getMonth()
 
   return yearDiff * 12 + monthDiff
 }

src/differenceInCalendarMonths/test.js → src/differenceInCalendarMonths/test.ts

@@ -1,104 +1,103 @@
-// @flow
 /* eslint-env mocha */
 
 import assert from 'power-assert'
 import differenceInCalendarMonths from '.'
 
-describe('differenceInCalendarMonths', function() {
-  it('returns the number of calendar months between the given dates', function() {
-    var result = differenceInCalendarMonths(
+describe('differenceInCalendarMonths', function () {
+  it('returns the number of calendar months between the given dates', function () {
+    const result = differenceInCalendarMonths(
       new Date(2012, 6 /* Jul */, 2, 18, 0),
       new Date(2011, 6 /* Jul */, 2, 6, 0)
     )
     assert(result === 12)
   })
 
-  it('returns a negative number if the time value of the first date is smaller', function() {
-    var result = differenceInCalendarMonths(
+  it('returns a negative number if the time value of the first date is smaller', function () {
+    const result = differenceInCalendarMonths(
       new Date(2011, 6 /* Jul */, 2, 6, 0),
       new Date(2012, 6 /* Jul */, 2, 18, 0)
     )
     assert(result === -12)
   })
 
-  it('accepts timestamps', function() {
-    var result = differenceInCalendarMonths(
+  it('accepts timestamps', function () {
+    const result = differenceInCalendarMonths(
       new Date(2014, 7 /* Aug */, 2).getTime(),
       new Date(2010, 6 /* Jul */, 2).getTime()
     )
     assert(result === 49)
   })
 
-  describe('edge cases', function() {
-    it('the difference is less than a month, but the given dates are in different calendar months', function() {
-      var result = differenceInCalendarMonths(
+  describe('edge cases', function () {
+    it('the difference is less than a month, but the given dates are in different calendar months', function () {
+      const result = differenceInCalendarMonths(
         new Date(2014, 8 /* Sep */, 1),
         new Date(2014, 7 /* Aug */, 31)
       )
       assert(result === 1)
     })
 
-    it('the same for the swapped dates', function() {
-      var result = differenceInCalendarMonths(
+    it('the same for the swapped dates', function () {
+      const result = differenceInCalendarMonths(
         new Date(2014, 7 /* Aug */, 31),
         new Date(2014, 8 /* Sep */, 1)
       )
       assert(result === -1)
     })
 
-    it('the days of months of the given dates are the same', function() {
-      var result = differenceInCalendarMonths(
+    it('the days of months of the given dates are the same', function () {
+      const result = differenceInCalendarMonths(
         new Date(2014, 8 /* Sep */, 6),
         new Date(2014, 7 /* Aug */, 6)
       )
       assert(result === 1)
     })
 
-    it('the given dates are the same', function() {
-      var result = differenceInCalendarMonths(
+    it('the given dates are the same', function () {
+      const result = differenceInCalendarMonths(
         new Date(2014, 8 /* Sep */, 5, 0, 0),
         new Date(2014, 8 /* Sep */, 5, 0, 0)
       )
       assert(result === 0)
     })
 
     it('does not return -0 when the given dates are the same', () => {
-      function isNegativeZero(x) {
+      function isNegativeZero(x: number): boolean {
         return x === 0 && 1 / x < 0
       }
 
-      var result = differenceInCalendarMonths(
+      const result = differenceInCalendarMonths(
         new Date(2014, 8 /* Sep */, 5, 0, 0),
         new Date(2014, 8 /* Sep */, 5, 0, 0)
       )
 
-      var resultIsNegative = isNegativeZero(result)
+      const resultIsNegative = isNegativeZero(result)
       assert(resultIsNegative === false)
     })
   })
 
-  it('returns NaN if the first date is `Invalid Date`', function() {
-    var result = differenceInCalendarMonths(
+  it('returns NaN if the first date is `Invalid Date`', function () {
+    const result = differenceInCalendarMonths(
       new Date(NaN),
       new Date(2017, 0 /* Jan */, 1)
     )
     assert(isNaN(result))
   })
 
-  it('returns NaN if the second date is `Invalid Date`', function() {
-    var result = differenceInCalendarMonths(
+  it('returns NaN if the second date is `Invalid Date`', function () {
+    const result = differenceInCalendarMonths(
       new Date(2017, 0 /* Jan */, 1),
       new Date(NaN)
     )
     assert(isNaN(result))
   })
 
-  it('returns NaN if the both dates are `Invalid Date`', function() {
-    var result = differenceInCalendarMonths(new Date(NaN), new Date(NaN))
+  it('returns NaN if the both dates are `Invalid Date`', function () {
+    const result = differenceInCalendarMonths(new Date(NaN), new Date(NaN))
     assert(isNaN(result))
   })
 
-  it('throws TypeError exception if passed less than 2 arguments', function() {
+  it('throws TypeError exception if passed less than 2 arguments', function () {
     assert.throws(differenceInCalendarMonths.bind(null), TypeError)
     assert.throws(differenceInCalendarMonths.bind(null, 1), TypeError)
   })