Improved performance on rendering 'day' with highlighted days

src/calendar.jsx

@@ -57,7 +57,7 @@ export default class Calendar extends React.Component {
     filterDate: PropTypes.func,
     fixedHeight: PropTypes.bool,
     formatWeekNumber: PropTypes.func,
-    highlightDates: PropTypes.array,
+    highlightDates: PropTypes.instanceOf(Map),
     includeDates: PropTypes.array,
     inline: PropTypes.bool,
     locale: PropTypes.string,
@@ -114,7 +114,10 @@ export default class Calendar extends React.Component {
   }
 
   componentDidMount () {
-    /* monthContainer height is needed in time component to determine the height for the ul in the time component. setState here so height is given after final component layout is rendered */
+    // monthContainer height is needed in time component
+    // to determine the height for the ul in the time component
+    // setState here so height is given after final component
+    // layout is rendered
     if (this.props.showTimeSelect) {
       this.assignMonthContainer = (() => {
         this.setState({monthContainer: this.monthContainer})

src/date_utils.js

@@ -376,3 +376,37 @@ export function getEffectiveMaxDate ({ maxDate, includeDates }) {
     return maxDate
   }
 }
+
+export function getHightLightDaysMap (
+  highlightDates = [],
+  defaultClassName = 'react-datepicker__day--highlighted'
+) {
+  const dateClasses = new Map()
+  for (let i = 0, len = highlightDates.length; i < len; i++) {
+    const obj = highlightDates[i]
+    if (isMoment(obj)) {
+      const key = obj.format('MM.DD.YYYY')
+      const classNamesArr = dateClasses.get(key) || []
+      if (!classNamesArr.includes(defaultClassName)) {
+        classNamesArr.push(defaultClassName)
+        dateClasses.set(key, classNamesArr)
+      }
+    } else if (typeof obj === 'object') {
+      const keys = Object.keys(obj)
+      const className = keys[0]
+      const arrOfMoments = obj[keys[0]]
+      if (typeof className === 'string' && arrOfMoments.constructor === Array) {
+        for (let k = 0, len = arrOfMoments.length; k < len; k++) {
+          const key = arrOfMoments[k].format('MM.DD.YYYY')
+          const classNamesArr = dateClasses.get(key) || []
+          if (!classNamesArr.includes(className)) {
+            classNamesArr.push(className)
+            dateClasses.set(key, classNamesArr)
+          }
+        }
+      }
+    }
+  }
+
+  return dateClasses
+}

src/day.jsx

@@ -6,8 +6,6 @@ import {
   getMonth,
   getDate,
   now,
-  isMoment,
-
   isSameDay,
   isDayDisabled,
   isDayInRange,
@@ -19,7 +17,7 @@ export default class Day extends React.Component {
     day: PropTypes.object.isRequired,
     dayClassName: PropTypes.func,
     endDate: PropTypes.object,
-    highlightDates: PropTypes.array,
+    highlightDates: PropTypes.instanceOf(Map),
     inline: PropTypes.bool,
     month: PropTypes.number,
     onClick: PropTypes.func,
@@ -56,30 +54,12 @@ export default class Day extends React.Component {
     const { day, highlightDates } = this.props
 
     if (!highlightDates) {
-      return {[defaultClassName]: false}
-    }
-
-    const classNames = {}
-    for (let i = 0, len = highlightDates.length; i < len; i++) {
-      const obj = highlightDates[i]
-      if (isMoment(obj)) {
-        if (isSameDay(day, obj)) {
-          classNames[defaultClassName] = true
-        }
-      } else if (typeof obj === 'object') {
-        const keys = Object.keys(obj)
-        const arr = obj[keys[0]]
-        if (typeof keys[0] === 'string' && arr.constructor === Array) {
-          for (let k = 0, len = arr.length; k < len; k++) {
-            if (isSameDay(day, arr[k])) {
-              classNames[keys[0]] = true
-            }
-          }
-        }
-      }
+      return false
     }
 
-    return classNames
+    // Looking for className in the Map of {'day string, 'className'}
+    const dayStr = day.format('MM.DD.YYYY')
+    return highlightDates.get(dayStr)
   }
 
   isInRange = () => {

src/index.jsx

@@ -24,14 +24,14 @@ import {
   subtractMonths,
   subtractWeeks,
   subtractYears,
-
   isSameDay,
   isDayDisabled,
   isDayInRange,
   getEffectiveMinDate,
   getEffectiveMaxDate,
   parseDate,
-  safeDateFormat
+  safeDateFormat,
+  getHightLightDaysMap
 } from './date_utils'
 import onClickOutside from 'react-onclickoutside'
 
@@ -156,6 +156,9 @@ export default class DatePicker extends React.Component {
     if (this.props.inline && currentMonth !== nextMonth) {
       this.setPreSelection(nextProps.selected)
     }
+    if (this.props.highlightDates !== nextProps.highlightDates) {
+      this.setState({'highlightDates': getHightLightDaysMap(nextProps.highlightDates)})
+    }
   }
 
   componentWillUnmount () {
@@ -177,11 +180,13 @@ export default class DatePicker extends React.Component {
       minDate && isBefore(defaultPreSelection, minDate) ? minDate
         : maxDate && isAfter(defaultPreSelection, maxDate) ? maxDate
           : defaultPreSelection
-
     return {
       open: this.props.startOpen || false,
       preventFocus: false,
-      preSelection: this.props.selected ? newDate(this.props.selected) : boundedPreSelection
+      preSelection: this.props.selected ? newDate(this.props.selected) : boundedPreSelection,
+      // transforming highlighted days (perhaps nested array)
+      // to flat Map for faster access in day.jsx
+      highlightDates: getHightLightDaysMap(this.props.highlightDates)
     }
   }
 
@@ -424,7 +429,7 @@ export default class DatePicker extends React.Component {
       filterDate={this.props.filterDate}
       onClickOutside={this.handleCalendarClickOutside}
       formatWeekNumber={this.props.formatWeekNumber}
-      highlightDates={this.props.highlightDates}
+      highlightDates={this.state.highlightDates}
       includeDates={this.props.includeDates}
       inline={this.props.inline}
       peekNextMonth={this.props.peekNextMonth}

src/month.jsx

@@ -15,7 +15,7 @@ export default class Month extends React.Component {
     filterDate: PropTypes.func,
     fixedHeight: PropTypes.bool,
     formatWeekNumber: PropTypes.func,
-    highlightDates: PropTypes.array,
+    highlightDates: PropTypes.instanceOf(Map),
     includeDates: PropTypes.array,
     inline: PropTypes.bool,
     maxDate: PropTypes.object,

src/week.jsx

@@ -12,7 +12,7 @@ export default class Week extends React.Component {
     excludeDates: PropTypes.array,
     filterDate: PropTypes.func,
     formatWeekNumber: PropTypes.func,
-    highlightDates: PropTypes.array,
+    highlightDates: PropTypes.instanceOf(Map),
     includeDates: PropTypes.array,
     inline: PropTypes.bool,
     maxDate: PropTypes.object,

test/day_test.js

@@ -1,7 +1,7 @@
 import React from 'react'
 import Day from '../src/day'
 import { shallow } from 'enzyme'
-import { getDayOfWeekCode, newDate, getDate, cloneDate, addDays, subtractDays, getMonth, newDateWithOffset } from '../src/date_utils'
+import { getDayOfWeekCode, newDate, getDate, cloneDate, addDays, subtractDays, getMonth, newDateWithOffset, getHightLightDaysMap } from '../src/date_utils'
 
 function renderDay (day, props = {}) {
   return shallow(
@@ -86,7 +86,8 @@ describe('Day', () => {
       const highlightDay1 = cloneDate(day)
       const highlightDay2 = addDays(cloneDate(day), 1)
       const highlightDates = [highlightDay1, highlightDay2]
-      const shallowDay = renderDay(day, { highlightDates })
+      const highlightDatesMap = getHightLightDaysMap(highlightDates)
+      const shallowDay = renderDay(day, { highlightDates: highlightDatesMap })
       expect(shallowDay.hasClass(className)).to.equal(true)
     })
 
@@ -95,18 +96,20 @@ describe('Day', () => {
       const highlightDay1 = subtractDays(cloneDate(day), 1)
       const highlightDay2 = addDays(cloneDate(day), 1)
       const highlightDates = [highlightDay1, highlightDay2]
-      const shallowDay = renderDay(day, { highlightDates })
+      const highlightDatesMap = getHightLightDaysMap(highlightDates)
+      const shallowDay = renderDay(day, { highlightDates: highlightDatesMap })
       expect(shallowDay.hasClass(className)).to.equal(false)
     })
 
-    describe('highlighted prop is an array of objects with class name as a key and array of moments as a value', () => {
+    describe('prop is an array of objects with class name as a key and array of moments as a value', () => {
       it('should apply the highlighted class if in highlighted', () => {
         const day = newDate()
         const highlightDay1 = {'testClassName': [addDays(cloneDate(day), 1), cloneDate(day)]}
         const highlightDay2 = addDays(cloneDate(day), 2)
         const highlightDay3 = addDays(cloneDate(day), 3)
         const highlightDates = [highlightDay1, highlightDay2, highlightDay3]
-        const shallowDay = renderDay(day, { highlightDates })
+        const highlightDatesMap = getHightLightDaysMap(highlightDates)
+        const shallowDay = renderDay(day, { highlightDates: highlightDatesMap })
         expect(shallowDay.hasClass('testClassName')).to.equal(true)
       })
 
@@ -116,7 +119,8 @@ describe('Day', () => {
         const highlightDay2 = addDays(cloneDate(day), 3)
         const highlightDay3 = addDays(cloneDate(day), 4)
         const highlightDates = [highlightDay1, highlightDay2, highlightDay3]
-        const shallowDay = renderDay(day, { highlightDates })
+        const highlightDatesMap = getHightLightDaysMap(highlightDates)
+        const shallowDay = renderDay(day, { highlightDates: highlightDatesMap })
         expect(shallowDay.hasClass('testClassName')).to.equal(false)
       })
 
@@ -126,10 +130,11 @@ describe('Day', () => {
         const highlightDay2 = {'barClassName': [cloneDate(day)]}
         const highlightDay3 = cloneDate(day)
         const highlightDates = [highlightDay1, highlightDay2, highlightDay3]
-        const shallowDay = renderDay(day, { highlightDates })
+        const highlightDatesMap = getHightLightDaysMap(highlightDates)
+        const shallowDay = renderDay(day, { highlightDates: highlightDatesMap })
         expect(shallowDay.hasClass('fooClassName')).to.equal(true)
         expect(shallowDay.hasClass('barClassName')).to.equal(true)
-        expect(shallowDay.hasClass('react-datepicker__day--highlighted')).to.equal(true)
+        expect(shallowDay.hasClass(className)).to.equal(true)
       })
     })
   })