convert getWeekOfMonth to TypeScript (date-fns#2598)

src/getWeekOfMonth/index.js → src/getWeekOfMonth/index.ts

@@ -1,8 +1,9 @@
 import getDate from '../getDate/index'
 import getDay from '../getDay/index'
 import startOfMonth from '../startOfMonth/index'
-import toInteger from '../_lib/toInteger/index'
+import type { LocaleOptions, WeekStartOptions } from '../types'
 import requiredArgs from '../_lib/requiredArgs/index'
+import toInteger from '../_lib/toInteger/index'
 
 /**
  * @name getWeekOfMonth
@@ -22,51 +23,38 @@ import requiredArgs from '../_lib/requiredArgs/index'
  * @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
  * @returns {Number} the week of month
  * @throws {TypeError} 1 argument required
- * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
+ * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6 inclusively
  *
  * @example
  * // Which week of the month is 9 November 2017?
- * var result = getWeekOfMonth(new Date(2017, 10, 9))
+ * const result = getWeekOfMonth(new Date(2017, 10, 9))
  * //=> 2
  */
-export default function getWeekOfMonth(date, dirtyOptions) {
+export default function getWeekOfMonth(
+  date: Date | number,
+  options?: LocaleOptions & WeekStartOptions
+): number {
   requiredArgs(1, arguments)
 
-  var options = dirtyOptions || {}
-  var locale = options.locale
-  var localeWeekStartsOn =
-    locale && locale.options && locale.options.weekStartsOn
-  var defaultWeekStartsOn =
-    localeWeekStartsOn == null ? 0 : toInteger(localeWeekStartsOn)
-  var weekStartsOn =
-    options.weekStartsOn == null
-      ? defaultWeekStartsOn
+  const defaultWeekStartsOn = options?.locale?.options?.weekStartsOn || 0
+
+  const weekStartsOn =
+    options?.weekStartsOn == null
+      ? toInteger(defaultWeekStartsOn)
       : toInteger(options.weekStartsOn)
 
-  // Test if weekStartsOn is between 0 and 6 _and_ is not NaN
   if (!(weekStartsOn >= 0 && weekStartsOn <= 6)) {
     throw new RangeError('weekStartsOn must be between 0 and 6 inclusively')
   }
 
-  var currentDayOfMonth = getDate(date)
-  if (isNaN(currentDayOfMonth)) {
-    return currentDayOfMonth
-  }
+  const currentDayOfMonth = getDate(date)
+  if (isNaN(currentDayOfMonth)) return NaN
 
-  var startWeekDay = getDay(startOfMonth(date))
-  var lastDayOfFirstWeek = 0
+  const startWeekDay = getDay(startOfMonth(date))
 
-  if (startWeekDay >= weekStartsOn) {
-    lastDayOfFirstWeek = weekStartsOn + 7 - startWeekDay
-  } else {
-    lastDayOfFirstWeek = weekStartsOn - startWeekDay
-  }
-
-  var weekNumber = 1
+  let lastDayOfFirstWeek = weekStartsOn - startWeekDay
+  if (lastDayOfFirstWeek <= 0) lastDayOfFirstWeek += 7
 
-  if (currentDayOfMonth > lastDayOfFirstWeek) {
-    var remainingDaysAfterFirstWeek = currentDayOfMonth - lastDayOfFirstWeek
-    weekNumber = weekNumber + Math.ceil(remainingDaysAfterFirstWeek / 7)
-  }
-  return weekNumber
+  const remainingDaysAfterFirstWeek = currentDayOfMonth - lastDayOfFirstWeek
+  return Math.ceil(remainingDaysAfterFirstWeek / 7) + 1
 }

src/getWeekOfMonth/test.js → src/getWeekOfMonth/test.ts

@@ -1,48 +1,47 @@
-// @flow
 /* eslint-env mocha */
 
-import assert from 'power-assert'
+import assert from 'assert'
 import getWeekOfMonth from '.'
 
 describe('getWeekOfMonth', function () {
   it('returns the week of the month of the given date', function () {
-    var result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 15))
+    const result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 15))
     assert(result === 3)
   })
 
   describe('edge cases', function () {
     describe('when the given day is the first of a month', function () {
       it('returns the week of the month of the given date', function () {
-        var result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 1))
+        const result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 1))
         assert(result === 1)
       })
     })
 
     describe('when the given day is the last of a month #1', function () {
       it('returns the week of the month of the given date', function () {
-        var result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 30))
+        const result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 30))
         assert(result === 5)
       })
     })
 
     describe('when the given day is the last of a month #2', function () {
       it('returns the week of the month of the given date', function () {
-        var result = getWeekOfMonth(new Date(2017, 9 /* Oct */, 31))
+        const result = getWeekOfMonth(new Date(2017, 9 /* Oct */, 31))
         assert(result === 5)
       })
     })
   })
 
   it('allows to specify which day is the first day of the week', function () {
-    var result = getWeekOfMonth(new Date(2017, 9 /* Oct */, 1), {
+    const result = getWeekOfMonth(new Date(2017, 9 /* Oct */, 1), {
       weekStartsOn: 1,
     })
     assert(result === 1)
   })
 
   it('allows to specify which day is the first day of the week in locale', function () {
-    var result = getWeekOfMonth(new Date(2017, 9 /* Oct */, 31), {
-      // $ExpectedMistake
+    const result = getWeekOfMonth(new Date(2017, 9 /* Oct */, 31), {
+      // @ts-expect-error
       locale: {
         options: { weekStartsOn: 1 },
       },
@@ -51,9 +50,9 @@ describe('getWeekOfMonth', function () {
   })
 
   it('`options.weekStartsOn` overwrites the first day of the week specified in locale', function () {
-    var result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 13), {
+    const result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 13), {
       weekStartsOn: 1,
-      // $ExpectedMistake
+      // @ts-expect-error
       locale: {
         options: { weekStartsOn: 0 },
       },
@@ -62,29 +61,43 @@ describe('getWeekOfMonth', function () {
   })
 
   it('accepts a timestamp', function () {
-    var result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 1).getTime())
+    const result = getWeekOfMonth(new Date(2017, 10 /* Nov */, 1).getTime())
     assert(result === 1)
   })
 
+  it('throws RangeError exception if `weekStartsOn` is out of bound', function () {
+    assert.throws(
+      // @ts-expect-error
+      getWeekOfMonth.bind(null, new Date(2019, 4 /* May */, 5), {
+        weekStartsOn: 7,
+      }),
+      RangeError
+    )
+  })
+
   it('returns NaN if the given date is invalid', function () {
-    var result = getWeekOfMonth(new Date(NaN))
+    const result = getWeekOfMonth(new Date(NaN))
     assert(isNaN(result))
   })
 
   it('throws TypeError exception if passed less than 1 argument', function () {
+    // @ts-expect-error
     assert.throws(getWeekOfMonth.bind(null), TypeError)
   })
 
   it('throws RangeError exception weekStartsOn is NaN', function () {
     try {
-      getWeekOfMonth(new Date(2017, 10 /* Nov */, 1), { weekStartsOn: NaN })
+      getWeekOfMonth(new Date(2017, 10 /* Nov */, 1), {
+        // @ts-expect-error
+        weekStartsOn: NaN,
+      })
     } catch (e) {
       assert(e instanceof RangeError)
     }
   })
 
   it('returns the week of the month of the given date, when the given date is sunday', function () {
-    var result = getWeekOfMonth(new Date(2019, 4 /* May */, 5), {
+    const result = getWeekOfMonth(new Date(2019, 4 /* May */, 5), {
       weekStartsOn: 1,
     })
     assert(result === 1)