Chart.js date adapter using dayjs (UTC Version)

index.js

import Chart from 'chart.js'
import dayjs from 'dayjs'
import customParseFormat from 'dayjs/plugin/customParseFormat'
import isoWeek from 'dayjs/plugin/isoWeek'
import utc from 'dayjs/plugin/utc'
dayjs.extend(customParseFormat)
dayjs.extend(isoWeek)
dayjs.extend(utc)

const FORMATS = {
  datetime: 'MMM D, YYYY, h:mm:ss a',
  millisecond: 'h:mm:ss.SSS a',
  second: 'h:mm:ss a',
  minute: 'h:mm a',
  hour: 'hA',
  day: 'MMM D',
  week: 'll',
  month: 'MMM YYYY',
  quarter: '[Q]Q - YYYY',
  year: 'YYYY',
}

Chart._adapters._date.override({
  _id: 'dayjs-utc', // DEBUG ONLY

  formats: function() {
    return FORMATS
  },

  parse: function(value, format) {
    if (Chart.helpers.isNullOrUndef(value)) return null
    if (typeof value === 'string' && typeof format === 'string') {
      value = dayjs.utc(value, format)
    } else if (!(value instanceof dayjs)) {
      value = dayjs.utc(value)
    }
    return value.isValid() ? value.valueOf() : null
  },

  format: function(time, format) {
    return dayjs.utc(time).format(format)
  },

  add: function(time, amount, unit) {
    return dayjs.utc(time).add(amount, unit).valueOf()
  },

  diff: function(max, min, unit) {
    return dayjs.utc(max).diff(dayjs.utc(min), unit)
  },

  startOf: function(time, unit, weekday) {
    if (unit === 'isoWeek') return dayjs.utc(time).isoWeekday(weekday).valueOf()
    return dayjs.utc(time).startOf(unit).valueOf()
  },

  endOf: function(time, unit) {
    return dayjs.utc(time).endOf(unit).valueOf()
  },
})