PHP's strrev in JavaScript

How to use

You you can install via yarn add locutus and require this function via const strrev = require('locutus/php/strings/strrev').

It is important to use a bundler that supports tree-shaking so that you only ship the functions that you actually use to your browser, instead of all of Locutus, which is massive. Examples are: Parcel, webpack, or rollup.js. For server-side use this is typically less of a concern.

Examples

Please note that these examples are distilled from test cases that automatically verify our functions still work correctly. This could explain some quirky ones.

#	code	expected result
1	strrev('Kevin van Zonneveld')	'dlevennoZ nav niveK'
2	strrev('a\u0301haB')	'Baha\u0301' // combining
3	strrev('A\uD87E\uDC04Z')	'Z\uD87E\uDC04A' // surrogates

Here’s what our current JavaScript equivalent to PHP's strrev looks like.

module.exports = function strrev(string) {
  //       discuss at: https://locutus.io/php/strrev/
  //      original by: Kevin van Zonneveld (https://kvz.io)
  //      bugfixed by: Onno Marsman (https://twitter.com/onnomarsman)
  // reimplemented by: Brett Zamir (https://brett-zamir.me)
  //        example 1: strrev('Kevin van Zonneveld')
  //        returns 1: 'dlevennoZ nav niveK'
  //        example 2: strrev('a\u0301haB')
  //        returns 2: 'Baha\u0301' // combining
  //        example 3: strrev('A\uD87E\uDC04Z')
  //        returns 3: 'Z\uD87E\uDC04A' // surrogates
  //             test: 'skip-3'

  string = string + ''

  // Performance will be enhanced with the next two lines of code commented
  // out if you don't care about combining characters
  // Keep Unicode combining characters together with the character preceding
  // them and which they are modifying (as in PHP 6)
  // See https://unicode.org/reports/tr44/#Property_Table (Me+Mn)
  // We also add the low surrogate range at the beginning here so it will be
  // maintained with its preceding high surrogate

  const chars = [
    '\uDC00-\uDFFF',
    '\u0300-\u036F',
    '\u0483-\u0489',
    '\u0591-\u05BD',
    '\u05BF',
    '\u05C1',
    '\u05C2',
    '\u05C4',
    '\u05C5',
    '\u05C7',
    '\u0610-\u061A',
    '\u064B-\u065E',
    '\u0670',
    '\u06D6-\u06DC',
    '\u06DE-\u06E4',
    '\u06E7\u06E8',
    '\u06EA-\u06ED',
    '\u0711',
    '\u0730-\u074A',
    '\u07A6-\u07B0',
    '\u07EB-\u07F3',
    '\u0901-\u0903',
    '\u093C',
    '\u093E-\u094D',
    '\u0951-\u0954',
    '\u0962',
    '\u0963',
    '\u0981-\u0983',
    '\u09BC',
    '\u09BE-\u09C4',
    '\u09C7',
    '\u09C8',
    '\u09CB-\u09CD',
    '\u09D7',
    '\u09E2',
    '\u09E3',
    '\u0A01-\u0A03',
    '\u0A3C',
    '\u0A3E-\u0A42',
    '\u0A47',
    '\u0A48',
    '\u0A4B-\u0A4D',
    '\u0A51',
    '\u0A70',
    '\u0A71',
    '\u0A75',
    '\u0A81-\u0A83',
    '\u0ABC',
    '\u0ABE-\u0AC5',
    '\u0AC7-\u0AC9',
    '\u0ACB-\u0ACD',
    '\u0AE2',
    '\u0AE3',
    '\u0B01-\u0B03',
    '\u0B3C',
    '\u0B3E-\u0B44',
    '\u0B47',
    '\u0B48',
    '\u0B4B-\u0B4D',
    '\u0B56',
    '\u0B57',
    '\u0B62',
    '\u0B63',
    '\u0B82',
    '\u0BBE-\u0BC2',
    '\u0BC6-\u0BC8',
    '\u0BCA-\u0BCD',
    '\u0BD7',
    '\u0C01-\u0C03',
    '\u0C3E-\u0C44',
    '\u0C46-\u0C48',
    '\u0C4A-\u0C4D',
    '\u0C55',
    '\u0C56',
    '\u0C62',
    '\u0C63',
    '\u0C82',
    '\u0C83',
    '\u0CBC',
    '\u0CBE-\u0CC4',
    '\u0CC6-\u0CC8',
    '\u0CCA-\u0CCD',
    '\u0CD5',
    '\u0CD6',
    '\u0CE2',
    '\u0CE3',
    '\u0D02',
    '\u0D03',
    '\u0D3E-\u0D44',
    '\u0D46-\u0D48',
    '\u0D4A-\u0D4D',
    '\u0D57',
    '\u0D62',
    '\u0D63',
    '\u0D82',
    '\u0D83',
    '\u0DCA',
    '\u0DCF-\u0DD4',
    '\u0DD6',
    '\u0DD8-\u0DDF',
    '\u0DF2',
    '\u0DF3',
    '\u0E31',
    '\u0E34-\u0E3A',
    '\u0E47-\u0E4E',
    '\u0EB1',
    '\u0EB4-\u0EB9',
    '\u0EBB',
    '\u0EBC',
    '\u0EC8-\u0ECD',
    '\u0F18',
    '\u0F19',
    '\u0F35',
    '\u0F37',
    '\u0F39',
    '\u0F3E',
    '\u0F3F',
    '\u0F71-\u0F84',
    '\u0F86',
    '\u0F87',
    '\u0F90-\u0F97',
    '\u0F99-\u0FBC',
    '\u0FC6',
    '\u102B-\u103E',
    '\u1056-\u1059',
    '\u105E-\u1060',
    '\u1062-\u1064',
    '\u1067-\u106D',
    '\u1071-\u1074',
    '\u1082-\u108D',
    '\u108F',
    '\u135F',
    '\u1712-\u1714',
    '\u1732-\u1734',
    '\u1752',
    '\u1753',
    '\u1772',
    '\u1773',
    '\u17B6-\u17D3',
    '\u17DD',
    '\u180B-\u180D',
    '\u18A9',
    '\u1920-\u192B',
    '\u1930-\u193B',
    '\u19B0-\u19C0',
    '\u19C8',
    '\u19C9',
    '\u1A17-\u1A1B',
    '\u1B00-\u1B04',
    '\u1B34-\u1B44',
    '\u1B6B-\u1B73',
    '\u1B80-\u1B82',
    '\u1BA1-\u1BAA',
    '\u1C24-\u1C37',
    '\u1DC0-\u1DE6',
    '\u1DFE',
    '\u1DFF',
    '\u20D0-\u20F0',
    '\u2DE0-\u2DFF',
    '\u302A-\u302F',
    '\u3099',
    '\u309A',
    '\uA66F-\uA672',
    '\uA67C',
    '\uA67D',
    '\uA802',
    '\uA806',
    '\uA80B',
    '\uA823-\uA827',
    '\uA880',
    '\uA881',
    '\uA8B4-\uA8C4',
    '\uA926-\uA92D',
    '\uA947-\uA953',
    '\uAA29-\uAA36',
    '\uAA43',
    '\uAA4C',
    '\uAA4D',
    '\uFB1E',
    '\uFE00-\uFE0F',
    '\uFE20-\uFE26',
  ]

  const graphemeExtend = new RegExp('(.)([' + chars.join('') + ']+)', 'g')

  // Temporarily reverse
  string = string.replace(graphemeExtend, '$2$1')
  return string.split('').reverse().join('')
}

A community effort

Not unlike Wikipedia, Locutus is an ongoing community effort. Our philosophy follows The McDonald’s Theory. This means that we assimilate first iterations with imperfections, hoping for others to take issue with-and improve them. This unorthodox approach has worked very well to foster fun and fruitful collaboration, but please be reminded to use our creations at your own risk. THE SOFTWARE IS PROVIDED "AS IS" has never been more true than for Locutus.

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