PHP's strftime in JavaScript

module.exports = functionstrftime (fmt, timestamp) {
//       discuss at: https://locutus.io/php/strftime/
//      original by: Blues (https://tech.bluesmoon.info/)
// reimplemented by: Brett Zamir (https://brett-zamir.me)
//         input by: Alex
//      bugfixed by: Brett Zamir (https://brett-zamir.me)
//      improved by: Brett Zamir (https://brett-zamir.me)
//           note 1: Uses global: locutus to store locale info
//        example 1: strftime("%A", 1062462400); // Return value will depend on date and locale
//        returns 1: 'Tuesday'
const setlocale = require('../strings/setlocale')
const $global = (typeofwindow !== 'undefined' ? window : global)
  $global.$locutus = $global.$locutus || {}
const $locutus = $global.$locutus
// ensure setup of localization variables takes place
  setlocale('LC_ALL', 0)
const _xPad = function (x, pad, r) {
if (typeof r === 'undefined') {
      r = 10
    }
for (; parseInt(x, 10) < r && r > 1; r /= 10) {
      x = pad.toString() + x
    }
return x.toString()
  }
const locale = $locutus.php.localeCategories.LC_TIME
const lcTime = $locutus.php.locales[locale].LC_TIME
var _formats = {
a: function (d) {
return lcTime.a[d.getDay()]
    },
A: function (d) {
return lcTime.A[d.getDay()]
    },
b: function (d) {
return lcTime.b[d.getMonth()]
    },
B: function (d) {
return lcTime.B[d.getMonth()]
    },
C: function (d) {
return _xPad(parseInt(d.getFullYear() / 100, 10), 0)
    },
d: ['getDate', '0'],
e: ['getDate', ' '],
g: function (d) {
return _xPad(parseInt(this.G(d) / 100, 10), 0)
    },
G: function (d) {
let y = d.getFullYear()
const V = parseInt(_formats.V(d), 10)
const W = parseInt(_formats.W(d), 10)
if (W > V) {
        y++
      } elseif (W === 0 && V >= 52) {
        y--
      }
return y
    },
H: ['getHours', '0'],
I: function (d) {
const I = d.getHours() % 12
return _xPad(I === 0 ? 12 : I, 0)
    },
j: function (d) {
let ms = d - newDate('' + d.getFullYear() + '/1/1 GMT')
// Line differs from Yahoo implementation which would be
// equivalent to replacing it here with:
      ms += d.getTimezoneOffset() * 60000
const doy = parseInt(ms / 60000 / 60 / 24, 10) + 1
return _xPad(doy, 0, 100)
    },
k: ['getHours', '0'],
// not in PHP, but implemented here (as in Yahoo)
    l: function (d) {
const l = d.getHours() % 12
return _xPad(l === 0 ? 12 : l, ' ')
    },
m: function (d) {
return _xPad(d.getMonth() + 1, 0)
    },
M: ['getMinutes', '0'],
p: function (d) {
return lcTime.p[d.getHours() >= 12 ? 1 : 0]
    },
P: function (d) {
return lcTime.P[d.getHours() >= 12 ? 1 : 0]
    },
s: function (d) {
// Yahoo uses return parseInt(d.getTime()/1000, 10);
returnDate.parse(d) / 1000
    },
S: ['getSeconds', '0'],
u: function (d) {
const dow = d.getDay()
return ((dow === 0) ? 7 : dow)
    },
U: function (d) {
const doy = parseInt(_formats.j(d), 10)
const rdow = 6 - d.getDay()
const woy = parseInt((doy + rdow) / 7, 10)
return _xPad(woy, 0)
    },
V: function (d) {
const woy = parseInt(_formats.W(d), 10)
const dow11 = (newDate('' + d.getFullYear() + '/1/1')).getDay()
// First week is 01 and not 00 as in the case of %U and %W,
// so we add 1 to the final result except if day 1 of the year
// is a Monday (then %W returns 01).
// We also need to subtract 1 if the day 1 of the year is
// Friday-Sunday, so the resulting equation becomes:
let idow = woy + (dow11 > 4 || dow11 <= 1 ? 0 : 1)
if (idow === 53 && (newDate('' + d.getFullYear() + '/12/31')).getDay() < 4) {
        idow = 1
      } elseif (idow === 0) {
        idow = _formats.V(newDate('' + (d.getFullYear() - 1) + '/12/31'))
      }
return _xPad(idow, 0)
    },
w: 'getDay',
W: function (d) {
const doy = parseInt(_formats.j(d), 10)
const rdow = 7 - _formats.u(d)
const woy = parseInt((doy + rdow) / 7, 10)
return _xPad(woy, 0, 10)
    },
y: function (d) {
return _xPad(d.getFullYear() % 100, 0)
    },
Y: 'getFullYear',
z: function (d) {
const o = d.getTimezoneOffset()
const H = _xPad(parseInt(Math.abs(o / 60), 10), 0)
const M = _xPad(o % 60, 0)
return (o > 0 ? '-' : '+') + H + M
    },
Z: function (d) {
return d.toString().replace(/^.*\(([^)]+)\)$/, '$1')
    },
'%': function (d) {
return'%'
    }
  }
const _date = (typeof timestamp === 'undefined')
    ? newDate()
    : (timestamp instanceofDate)
        ? newDate(timestamp)
        : newDate(timestamp * 1000)
const _aggregates = {
c: 'locale',
D: '%m/%d/%y',
F: '%y-%m-%d',
h: '%b',
n: '\n',
r: 'locale',
R: '%H:%M',
t: '\t',
T: '%H:%M:%S',
x: 'locale',
X: 'locale'
  }
// First replace aggregates (run in a loop because an agg may be made up of other aggs)
while (fmt.match(/%[cDFhnrRtTxX]/)) {
    fmt = fmt.replace(/%([cDFhnrRtTxX])/g, function (m0, m1) {
const f = _aggregates[m1]
return (f === 'locale' ? lcTime[m1] : f)
    })
  }
// Now replace formats - we need a closure so that the date object gets passed through
const str = fmt.replace(/%([aAbBCdegGHIjklmMpPsSuUVwWyYzZ%])/g, function (m0, m1) {
const f = _formats[m1]
if (typeof f === 'string') {
return _date[f]()
    } elseif (typeof f === 'function') {
return f(_date)
    } elseif (typeof f === 'object' && typeof f[0] === 'string') {
return _xPad(_date[f[0]](), f[1])
    } else {
// Shouldn't reach here
return m1
    }
  })
return str
}