5 files changed, 168 insertions, 0 deletions
diff --git a/date-fns/src/isSameMonth/benchmark.js b/date-fns/src/isSameMonth/benchmark.js
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index 0000000..dec2530
--- /dev/null
+++ b/date-fns/src/isSameMonth/benchmark.js
@@ -0,0 +1,23 @@
+// @flow
+/* eslint-env mocha */
+/* global suite, benchmark */
+
+import isSameMonth from '.'
+import moment from 'moment'
+
+suite('isSameMonth', function () {
+  benchmark('date-fns', function () {
+    return isSameMonth(this.dateA, this.dateB)
+  })
+
+  benchmark('Moment.js', function () {
+    return this.momentA.isSame(this.momentB, 'month')
+  })
+}, {
+  setup: function () {
+    this.dateA = new Date()
+    this.momentA = moment()
+    this.dateB = new Date(this.dateA.getTime() + 604800000)
+    this.momentB = this.momentA.clone().add(7, 'days')
+  }
+})
diff --git a/date-fns/src/isSameMonth/index.d.ts b/date-fns/src/isSameMonth/index.d.ts
new file mode 100644
index 0000000..bd0e886
--- /dev/null
+++ b/date-fns/src/isSameMonth/index.d.ts
@@ -0,0 +1,4 @@
+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+import { isSameMonth } from 'date-fns'
+export default isSameMonth
diff --git a/date-fns/src/isSameMonth/index.js.flow b/date-fns/src/isSameMonth/index.js.flow
new file mode 100644
index 0000000..55ea578
--- /dev/null
+++ b/date-fns/src/isSameMonth/index.js.flow
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+// @flow
+// This file is generated automatically by `scripts/build/typings.js`. Please, don't change it.
+
+export type Interval = {
+  start: Date | number,
+  end: Date | number,
+}
+
+export type Locale = {
+  code?: string,
+  formatDistance?: (...args: Array<any>) => any,
+  formatRelative?: (...args: Array<any>) => any,
+  localize?: {
+    ordinalNumber: (...args: Array<any>) => any,
+    era: (...args: Array<any>) => any,
+    quarter: (...args: Array<any>) => any,
+    month: (...args: Array<any>) => any,
+    day: (...args: Array<any>) => any,
+    dayPeriod: (...args: Array<any>) => any,
+  },
+  formatLong?: {
+    date: (...args: Array<any>) => any,
+    time: (...args: Array<any>) => any,
+    dateTime: (...args: Array<any>) => any,
+  },
+  match?: {
+    ordinalNumber: (...args: Array<any>) => any,
+    era: (...args: Array<any>) => any,
+    quarter: (...args: Array<any>) => any,
+    month: (...args: Array<any>) => any,
+    day: (...args: Array<any>) => any,
+    dayPeriod: (...args: Array<any>) => any,
+  },
+  options?: {
+    weekStartsOn?: 0 | 1 | 2 | 3 | 4 | 5 | 6,
+    firstWeekContainsDate?: 1 | 2 | 3 | 4 | 5 | 6 | 7,
+  },
+}
+
+export type Duration = {
+  years?: number,
+  months?: number,
+  weeks?: number,
+  days?: number,
+  hours?: number,
+  minutes?: number,
+  seconds?: number,
+}
+
+export type Day = 0 | 1 | 2 | 3 | 4 | 5 | 6
+
+declare module.exports: (
+  dateLeft: Date | number,
+  dateRight: Date | number
+) => boolean
diff --git a/date-fns/src/isSameMonth/index.ts b/date-fns/src/isSameMonth/index.ts
new file mode 100644
index 0000000..65058b1
--- /dev/null
+++ b/date-fns/src/isSameMonth/index.ts
@@ -0,0 +1,35 @@
+import toDate from '../toDate/index'
+import requiredArgs from '../_lib/requiredArgs/index'
+
+/**
+ * @name isSameMonth
+ * @category Month Helpers
+ * @summary Are the given dates in the same month?
+ *
+ * @description
+ * Are the given dates in the same month?
+ *
+ * ### v2.0.0 breaking changes:
+ *
+ * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
+ *
+ * @param {Date|Number} dateLeft - the first date to check
+ * @param {Date|Number} dateRight - the second date to check
+ * @returns {Boolean} the dates are in the same month
+ * @throws {TypeError} 2 arguments required
+ *
+ * @example
+ * // Are 2 September 2014 and 25 September 2014 in the same month?
+ * var result = isSameMonth(new Date(2014, 8, 2), new Date(2014, 8, 25))
+ * //=> true
+ */
+export default function isSameMonth(dirtyDateLeft: Date | number, dirtyDateRight: Date | number): boolean {
+  requiredArgs(2, arguments)
+
+  const dateLeft = toDate(dirtyDateLeft)
+  const dateRight = toDate(dirtyDateRight)
+  return (
+    dateLeft.getFullYear() === dateRight.getFullYear() &&
+    dateLeft.getMonth() === dateRight.getMonth()
+  )
+}
diff --git a/date-fns/src/isSameMonth/test.ts b/date-fns/src/isSameMonth/test.ts
new file mode 100644
index 0000000..23a8152
--- /dev/null
+++ b/date-fns/src/isSameMonth/test.ts
@@ -0,0 +1,51 @@
+// @flow
+/* eslint-env mocha */
+
+import assert from 'power-assert'
+import isSameMonth from '.'
+
+describe('isSameMonth', function() {
+  it('returns true if the given dates have the same month (and year)', function() {
+    const result = isSameMonth(
+      new Date(2014, 8 /* Sep */, 2),
+      new Date(2014, 8 /* Sep */, 25)
+    )
+    assert(result === true)
+  })
+
+  it('returns false if the given dates have different months', function() {
+    const result = isSameMonth(
+      new Date(2014, 8 /* Sep */, 2),
+      new Date(2013, 8 /* Sep */, 25)
+    )
+    assert(result === false)
+  })
+
+  it('accepts a timestamp', function() {
+    const result = isSameMonth(
+      new Date(2014, 8 /* Sep */, 2).getTime(),
+      new Date(2014, 8 /* Sep */, 25).getTime()
+    )
+    assert(result === true)
+  })
+
+  it('returns false if the first date is `Invalid Date`', function() {
+    const result = isSameMonth(new Date(NaN), new Date(1989, 6 /* Jul */, 10))
+    assert(result === false)
+  })
+
+  it('returns false if the second date is `Invalid Date`', function() {
+    const result = isSameMonth(new Date(1987, 1 /* Feb */, 11), new Date(NaN))
+    assert(result === false)
+  })
+
+  it('returns false if the both dates are `Invalid Date`', function() {
+    const result = isSameMonth(new Date(NaN), new Date(NaN))
+    assert(result === false)
+  })
+
+  it('throws TypeError exception if passed less than 2 arguments', function() {
+    assert.throws(isSameMonth.bind(null), TypeError)
+    assert.throws(isSameMonth.bind(null, 1), TypeError)
+  })
+})