Fake moment.js

fakemoment.ts

const moment = function moment(textValue: string | number, format: string) {
  const timeOfTheDay = /^([0-9]{1,2}):([0-9]{1,2})$/.exec((textValue || "").trim())
  const onlyTime = timeOfTheDay && new Date()
  if (onlyTime && timeOfTheDay) onlyTime.setHours(parseInt(timeOfTheDay[1]), parseInt(timeOfTheDay[2]))
  const date = !textValue ? new Date() :
    !isNaN(textValue as number) ? new Date(textValue) :
      !(textValue as string).trim() ? new Date() :
        onlyTime ? onlyTime : new Date(textValue)
  return {
    date,
    humanizedDiff: '',
    diffDays: 0,
    diffHours: 0,
    diffMinutes: 0,
    add: function (quantity: number, unit: 'day' | 'days' | 'month' | 'months' | 'year' | 'years') {
      const oneDay = 24 * 60 * 60 * 1000
      if (unit === 'day' || unit === 'days')
        this.date = new Date(this.date.getTime() + quantity * oneDay)
      return this
    },

    utcOffset: function (offset: any) {
      const oneHour = 60 * 60 * 1000
      const oneMinute = 60 * 60 * 1000
      if (!isNaN(offset)) {
        return this
      }
      const offsetText = (offset || "").toString()
      const regex = /^([+-]?)([0-9]{1,2})(?::([0-9]{1,2}))?$/
      const match = regex.exec(offsetText)
      if (!match) return this
      const sign = match[1] === "-" ? -1 : 1
      const hours = parseInt(match[2])
      const minutes = !match[3] ? 0 : parseInt(match[3])
      this.date = new Date(this.date.getTime() + sign * hours * oneHour
        + minutes * oneMinute)

      return this
    },

    toObject: function () {
      return {
        year: this.date.getFullYear(), month: this.date.getMonth() + 1, day: this.date.getDay(),
        hours: this.date.getHours(), minutes: this.date.getMinutes(), seconds: this.date.getSeconds()
      }
    },

    format: function (format: string) {
      const table = format.split(/(?=[^a-zA-Z])/)
      return table.map(
        (token, i) => {
          const rightPadding = table[i + 1] &&
            /^[a-zA-Z]/.exec(table[i + 1].trim()) ? ' ' : ''
          switch (token.trim()) {
            case 'LT': return `${this.date.getHours()}:${this.date.getMinutes()}${rightPadding}`
            case 'DD': return this.date.getDate() + rightPadding
            case 'YYYY': return this.date.getFullYear() + rightPadding
            case 'ddd': switch (this.date.getDay()) {
              case 0: return 'Sun' + rightPadding
              case 1: return 'Mon' + rightPadding
              case 2: return 'Tue' + rightPadding
              case 3: return 'Wed' + rightPadding
              case 4: return 'Thi' + rightPadding
              case 5: return 'Fri' + rightPadding
              case 6: return 'Sat' + rightPadding
              default: return "" + rightPadding
            }
            case 'MMM': switch (this.date.getMonth()) {
              case 0: return 'Jan' + rightPadding
              case 1: return 'Feb' + rightPadding
              case 2: return 'Mar' + rightPadding
              case 3: return 'Apr' + rightPadding
              case 4: return 'May' + rightPadding
              case 5: return 'Jun' + rightPadding
              case 6: return 'Jul' + rightPadding
              case 7: return 'Aug' + rightPadding
              case 8: return 'Sep' + rightPadding
              case 9: return 'Oct' + rightPadding
              case 10: return 'Nov' + rightPadding
              case 11: return 'Dec' + rightPadding
              default: return "" + rightPadding
            }
            default: return token + rightPadding;
          }
        }
      ).join('')
    },

    diff: function (otherMoment?: any, unit: 'day' | 'days' | 'month' | 'months' | 'year' | 'years') {
      if (!otherMoment || !otherMoment.date) return ""
      const oDate = otherMoment.date as Date;
      const diff = this.date.getTime() - oDate.getTime()
      this.diffDays = Math.floor(diff / 86400000)
      this.diffHours = Math.floor((diff - this.diffDays * 86400000) / 3600000)
      this.diffMinutes = (diff - this.diffDays * 86400000 - this.diffHours * 3600000) / 60000
      this.humanizedDiff = `${this.diffDays > 0 ? this.diffDays + ' days' : ''}${
        this.diffDays > 0 && this.diffHours > 0 ? ' ' : ''}${
        this.diffHours > 0 ? this.diffHours + ' hours' : ''}${this.diffHours > 0 && this.diffMinutes > 0 ? ' ' : ''}${
        this.diffMinutes > 0 ? this.diffMinutes + ' minutes' : ''}`;
      return unit === 'day' || unit === 'days' ? this.diffDays : this
    },

    humanize: function () {
      return this.humanizedDiff
    }
  }
}

const momentModule = Object.assign(moment, {
  duration: function (thisMoment?: any) {
    return thisMoment
  }
})

export default momentModule