Add addBusinessDays function (date-fns#1154)

CHANGELOG.md

@@ -761,6 +761,9 @@ for the list of changes made since `v2.0.0-alpha.1`.
 - [Add new function `differenceInBusinessDays`](https://github.com/date-fns/date-fns/pull/1194)
   which calculates the difference in business days. Kudos to [@ThorrStevens](https://github.com/ThorrStevens)!
 
+- [Add new function `addBusinessDays`](https://github.com/date-fns/date-fns/pull/1154),
+  similar to `addDays` but ignoring weekends. Thanks to [@ThorrStevens](https://github.com/ThorrStevens)!
+
 ## [1.30.1] - 2018-12-10
 
 ### Fixed

scripts/test/dst.sh

@@ -11,3 +11,4 @@ export PATH="$(yarn bin):$PATH"
 env TZ=America/Sao_Paulo babel-node ./test/dst/parseISO/basic.js
 env TZ=Pacific/Apia babel-node ./test/dst/parseISO/samoa.js
 env TZ=Asia/Damascus babel-node ./test/dst/eachDayOfInterval/basic.js
+env TZ=America/Santiago babel-node ./test/dst/addBusinessDays/basic.js

src/addBusinessDays/index.d.ts

@@ -0,0 +1,4 @@
+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+import { addBusinessDays } from 'date-fns'
+export default addBusinessDays

src/addBusinessDays/index.js

@@ -0,0 +1,44 @@
+import isWeekend from '../isWeekend/index.js'
+import toDate from '../toDate/index.js'
+import toInteger from '../_lib/toInteger/index.js'
+
+/**
+ * @name addBusinessDays
+ * @category Day Helpers
+ * @summary Add the specified number of business days (mon - fri) to the given date.
+ *
+ * @description
+ * Add the specified number of business days (mon - fri) to the given date, ignoring weekends.
+ *
+ * @param {Date|Number} date - the date to be changed
+ * @param {Number} amount - the amount of business days to be added
+ * @returns {Date} the new date with the business days added
+ * @throws {TypeError} 2 arguments required
+ *
+ * @example
+ * // Add 10 business days to 1 September 2014:
+ * var result = addBusinessDays(new Date(2014, 8, 1), 10)
+ * //=> Mon Sep 15 2014 00:00:00 (skipped weekend days)
+ */
+export default function addBusinessDays(dirtyDate, dirtyAmount) {
+  if (arguments.length < 2) {
+    throw new TypeError(
+      '2 arguments required, but only ' + arguments.length + ' present'
+    )
+  }
+
+  var date = toDate(dirtyDate)
+  var amount = toInteger(dirtyAmount)
+
+  if (isNaN(amount)) return new Date(NaN)
+
+  var hours = date.getHours()
+  var numWeekDays = 0
+  while (numWeekDays < amount) {
+    date.setDate(date.getDate() + 1)
+    date.setHours(hours)
+    if (!isWeekend(date)) numWeekDays++
+  }
+
+  return date
+}

src/addBusinessDays/index.js.flow

@@ -0,0 +1,38 @@
+// @flow
+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+type Interval = {
+  start: Date | number,
+  end: Date | number
+}
+
+type Locale = {
+  formatDistance: Function,
+  formatRelative: Function,
+  localize: {
+    ordinalNumber: Function,
+    era: Function,
+    quarter: Function,
+    month: Function,
+    day: Function,
+    dayPeriod: Function
+  },
+  formatLong: Object,
+  date: Function,
+  time: Function,
+  dateTime: Function,
+  match: {
+    ordinalNumber: Function,
+    era: Function,
+    quarter: Function,
+    month: Function,
+    day: Function,
+    dayPeriod: Function
+  },
+  options?: {
+    weekStartsOn?: 0 | 1 | 2 | 3 | 4 | 5 | 6,
+    firstWeekContainsDate?: 1 | 2 | 3 | 4 | 5 | 6 | 7
+  }
+}
+
+declare module.exports: (date: Date | number, amount: number) => Date

src/addBusinessDays/test.js

@@ -0,0 +1,49 @@
+// @flow
+/* eslint-env mocha */
+
+import assert from 'power-assert'
+import addBusinessDays from '.'
+
+describe('addBusinessDays', function() {
+  it('adds the given number of business days', function() {
+    var result = addBusinessDays(new Date(2014, 8 /* Sep */, 1), 10)
+    assert.deepEqual(result, new Date(2014, 8 /* Sep */, 15))
+  })
+
+  it('accepts a timestamp', function() {
+    var result = addBusinessDays(new Date(2014, 8 /* Sep */, 1).getTime(), 10)
+    assert.deepEqual(result, new Date(2014, 8 /* Sep */, 15))
+  })
+
+  it('converts a fractional number to an integer', function() {
+    var result = addBusinessDays(new Date(2014, 8 /* Sep */, 1), 10.5)
+    assert.deepEqual(result, new Date(2014, 8 /* Sep */, 15))
+  })
+
+  it('implicitly converts number arguments', function() {
+    // $ExpectedMistake
+    var result = addBusinessDays(new Date(2014, 8 /* Sep */, 1), '10')
+    assert.deepEqual(result, new Date(2014, 8 /* Sep */, 15))
+  })
+
+  it('does not mutate the original date', function() {
+    var date = new Date(2014, 8 /* Sep */, 1)
+    addBusinessDays(date, 11)
+    assert.deepEqual(date, new Date(2014, 8 /* Sep */, 1))
+  })
+
+  it('returns `Invalid Date` if the given date is invalid', function() {
+    var result = addBusinessDays(new Date(NaN), 10)
+    assert(result instanceof Date && isNaN(result))
+  })
+
+  it('returns `Invalid Date` if the given amount is NaN', function() {
+    var result = addBusinessDays(new Date(2014, 8 /* Sep */, 1), NaN)
+    assert(result instanceof Date && isNaN(result))
+  })
+
+  it('throws TypeError exception if passed less than 2 arguments', function() {
+    assert.throws(addBusinessDays.bind(null), TypeError)
+    assert.throws(addBusinessDays.bind(null, 1), TypeError)
+  })
+})

src/esm/fp/index.js

@@ -1,5 +1,6 @@
 // This file is generated automatically by `scripts/build/indices.js`. Please, don't change it.
 
+export { default as addBusinessDays } from './addBusinessDays/index.js'
 export { default as addDays } from './addDays/index.js'
 export { default as addHours } from './addHours/index.js'
 export { default as addISOWeekYears } from './addISOWeekYears/index.js'

src/esm/index.js

@@ -1,5 +1,6 @@
 // This file is generated automatically by `scripts/build/indices.js`. Please, don't change it.
 
+export { default as addBusinessDays } from './addBusinessDays/index.js'
 export { default as addDays } from './addDays/index.js'
 export { default as addHours } from './addHours/index.js'
 export { default as addISOWeekYears } from './addISOWeekYears/index.js'

src/fp/addBusinessDays/index.d.ts

@@ -0,0 +1,4 @@
+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+import { addBusinessDays } from 'date-fns/fp'
+export default addBusinessDays

src/fp/addBusinessDays/index.js

@@ -0,0 +1,8 @@
+// This file is generated automatically by `scripts/build/fp.js`. Please, don't change it.
+
+import fn from '../../addBusinessDays/index.js'
+import convertToFP from '../_lib/convertToFP/index.js'
+
+var addBusinessDays = convertToFP(fn, 2)
+
+export default addBusinessDays

src/fp/addBusinessDays/index.js.flow

@@ -0,0 +1,44 @@
+// @flow
+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+type Interval = {
+  start: Date | number,
+  end: Date | number
+}
+
+type Locale = {
+  formatDistance: Function,
+  formatRelative: Function,
+  localize: {
+    ordinalNumber: Function,
+    era: Function,
+    quarter: Function,
+    month: Function,
+    day: Function,
+    dayPeriod: Function
+  },
+  formatLong: Object,
+  date: Function,
+  time: Function,
+  dateTime: Function,
+  match: {
+    ordinalNumber: Function,
+    era: Function,
+    quarter: Function,
+    month: Function,
+    day: Function,
+    dayPeriod: Function
+  },
+  options?: {
+    weekStartsOn?: 0 | 1 | 2 | 3 | 4 | 5 | 6,
+    firstWeekContainsDate?: 1 | 2 | 3 | 4 | 5 | 6 | 7
+  }
+}
+
+type CurriedFn1<A, R> = <A>(a: A) => R
+
+type CurriedFn2<A, B, R> = <A>(
+  a: A
+) => CurriedFn1<B, R> | (<A, B>(a: A, b: B) => R)
+
+declare module.exports: CurriedFn2<number, Date | number, Date>

src/fp/index.js

@@ -3,6 +3,7 @@
 var constants = require('../constants/index.js')
 
 module.exports = {
+  addBusinessDays: require('./addBusinessDays/index.js'),
   addDays: require('./addDays/index.js'),
   addHours: require('./addHours/index.js'),
   addISOWeekYears: require('./addISOWeekYears/index.js'),

src/fp/index.js.flow

@@ -66,6 +66,7 @@ type CurriedFn4<A, B, C, D, R> = <A>(
         ) => CurriedFn1<D, R> | (<A, B, C, D>(a: A, b: B, c: C, d: D) => R)))
 
 declare module.exports: {
+  addBusinessDays: CurriedFn2<number, Date | number, Date>,
   addDays: CurriedFn2<number, Date | number, Date>,
   addHours: CurriedFn2<number, Date | number, Date>,
   addISOWeekYears: CurriedFn2<number, Date | number, Date>,

src/index.js

@@ -3,6 +3,7 @@
 var constants = require('./constants/index.js')
 
 module.exports = {
+  addBusinessDays: require('./addBusinessDays/index.js'),
   addDays: require('./addDays/index.js'),
   addHours: require('./addHours/index.js'),
   addISOWeekYears: require('./addISOWeekYears/index.js'),

src/index.js.flow

@@ -36,6 +36,8 @@ type Locale = {
 }
 
 declare module.exports: {
+  addBusinessDays: (date: Date | number, amount: number) => Date,
+
   addDays: (date: Date | number, amount: number) => Date,
 
   addHours: (date: Date | number, amount: number) => Date,

test/dst/addBusinessDays/basic.js

@@ -0,0 +1,18 @@
+// This is basic DST test for addBusinessDays
+
+import assert from 'assert'
+import addBusinessDays from '../../../src/addBusinessDays'
+
+if (process.env.TZ !== 'America/Santiago')
+  throw new Error('The test must be run with TZ=America/Santiago')
+
+if (parseInt(process.version.match(/^v(\d+)\./)[1]) < 10)
+  throw new Error('The test must be run on Node.js version >= 10')
+
+console.log(addBusinessDays(new Date(2014, 8 /* Sep */, 1), 10).toString())
+
+assert.deepEqual(
+  // new Date(2014, 8, 7) is the DST day
+  addBusinessDays(new Date(2014, 8 /* Sep */, 1), 10).toString(),
+  'Mon Sep 15 2014 00:00:00 GMT-0300 (Chile Summer Time)'
+)