Add relative date helpers (#299)

src/plugin/isToday/index.js

@@ -0,0 +1,11 @@
+export default (o, c, d) => {
+  const proto = c.prototype
+  proto.isToday = function () {
+    const comparisonKey = ['$y', '$D', '$m']
+    const now = d()
+
+    return comparisonKey.filter(function (key) {
+      return now[key] !== this[key]
+    }, this).length === 0
+  }
+}

src/plugin/isTomorrow/index.js

@@ -0,0 +1,12 @@
+export default (o, c, d) => {
+  const proto = c.prototype
+  proto.isTomorrow = function () {
+    const comparisonKey = ['$y', '$D', '$m']
+    const tomorrow = d().add(1, 'day')
+
+    return comparisonKey.filter(function (key) {
+      return tomorrow[key] === this[key]
+    }, this).length === 3
+  }
+}
+

src/plugin/isYesterday/index.js

@@ -0,0 +1,12 @@
+export default (o, c, d) => {
+  const proto = c.prototype
+  proto.isYesterday = function () {
+    const comparisonKey = ['$y', '$D', '$m']
+    const yesterday = d().subtract(1, 'day')
+
+    return comparisonKey.filter(function (key) {
+      return yesterday[key] === this[key]
+    }, this).length === 3
+  }
+}
+

test/plugin/isToday.test.js

@@ -0,0 +1,18 @@
+import MockDate from 'mockdate'
+import dayjs from '../../src'
+import isToday from '../../src/plugin/isToday'
+
+dayjs.extend(isToday)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('is today', () => {
+  expect(dayjs(new Date()).isToday()).toBeTruthy()
+  expect(dayjs('2017-01-01').isToday()).toBeFalsy()
+})

test/plugin/isTomorrow.test.js

@@ -0,0 +1,18 @@
+import MockDate from 'mockdate'
+import dayjs from '../../src'
+import isTomorrow from '../../src/plugin/isTomorrow'
+
+dayjs.extend(isTomorrow)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('is tomorrow', () => {
+  expect(dayjs().add(1, 'day').isTomorrow()).toBeTruthy()
+  expect(dayjs('2017-01-01').isTomorrow('2019-01-01', '2017-01-01')).toBeFalsy()
+})

test/plugin/isYesterday.test.js

@@ -0,0 +1,18 @@
+import MockDate from 'mockdate'
+import dayjs from '../../src'
+import isYesterday from '../../src/plugin/isYesterday'
+
+dayjs.extend(isYesterday)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('is yesterday', () => {
+  expect(dayjs().subtract(1, 'day').isYesterday()).toBeTruthy()
+  expect(dayjs('2017-01-01').isYesterday()).toBeFalsy()
+})