Time module.

constants.js

/**
 * Second in milliseconds.
 */
const SECOND = 1000

/**
 * Minute in milliseconds.
 */
const MINUTE = 60 * SECOND

/**
 * Hour in milliseconds.
 */
const HOUR = 60 * MINUTE

/**
 * Day in milliseconds.
 */
const DAY = 24 * HOUR

/**
 * Week in milliseconds.
 */
const WEEK = 7 * DAY

export { SECOND, MINUTE, HOUR, DAY, WEEK }

time.js

import { DAY, MINUTE } from './constants'
import { isType as is } from './type'

/**
 * Get time in milliseconds.
 * @param {string|number|Date} [date]
 * @returns {number}
 */
export const getTime = (date = null) => {
  const offset = +is(date, 'String') && new Date(date).getTimezoneOffset() * MINUTE
  const time = is(date, 'String') ? new Date(date).getTime() + offset
             : is(date, 'Date')   ? date.getTime()
             : is(date, 'Number') ? date
                                  : Date.now()
  return time
}

/**
 * Get time diff in type defined.
 * @param {Date}   from
 * @param {Date}   [to]
 * @param {number} [type]
 * @returns {number}
 */
export const getDiff = (from, to = new Date(), type = DAY) => {
  const diff = getTime(to) - getTime(from)
  const left = ~~(diff / type)
  return left
}

/**
 * @param {Date}   from
 * @param {Date}   [to]
 * @param {number} type
 * @returns {Array.<Date>}
 */
export const range = (from, to = new Date(), type = DAY) => {
  if (getTime(from) >= getTime(to))
    throw new Error('Invalid range, from value should be lower than to value.')

  const length = getDiff(from, to, type) + 1
  const range = Array.from({ length }, (_, index) => {
    const time = getTime(from) + index * type
    const date = new Date(time)
    return date
  })
  return range
}

/**
 * Date formats.
 * @type {Object.<string,function(Date):string>}
 */
const formats = {
  'D':    (date) => String(date.getDate()),
  'DD':   (date) => String(date.getDate()).padStart(2, '0'),
  'M':    (date) => String(date.getMonth() + 1),
  'MM':   (date) => String(date.getMonth() + 1).padStart(2, '0'),
  'YY':   (date) => String(date.getFullYear()).substring(2),
  'YYYY': (date) => String(date.getFullYear()).padStart(4, '0'),
  'HH':   (date) => String(date.getHours()).padStart(2, '0'),
  'mm':   (date) => String(date.getMinutes()).padStart(2, '0')
}

/**
 * Format date.
 * @param {string|number|Date} date
 * @param {string}             format
 * @returns {string}
 */
export const format = (date, format) => {
  const instance = new Date(getTime(date))
  const regex = new RegExp(Object.keys(formats).join('|'), 'g')
  const result = format.replace(regex, (format) => formats[format](instance))
  return result
}

export * from './constants'

type.js

/**
 * Get value's type name.
 * @param {*} value
 * @returns {string}
 */
export const getType = (value) => {
  const string = Object.prototype.toString.call(value)
  const [, type ] = /\[object (\w*)\]/.exec(string)
  return type
}

/**
 * Check if value's type is type (argument).
 * @param {*} value
 * @param {string} type
 * @returns {boolean}
 */
export const isType = (value, type) => getType(value) === type