PHP's quoted_printable_encode in JavaScript

module.exports = functionquoted_printable_encode (str) { // eslint-disable-line camelcase
//  discuss at: https://locutus.io/php/quoted_printable_encode/
// original by: Theriault (https://github.com/Theriault)
// improved by: Brett Zamir (https://brett-zamir.me)
// improved by: Theriault (https://github.com/Theriault)
//   example 1: quoted_printable_encode('a=b=c')
//   returns 1: 'a=3Db=3Dc'
//   example 2: quoted_printable_encode('abc   \r\n123   \r\n')
//   returns 2: 'abc  =20\r\n123  =20\r\n'
//   example 3: quoted_printable_encode('0123456789012345678901234567890123456789012345678901234567890123456789012345')
//   returns 3: '012345678901234567890123456789012345678901234567890123456789012345678901234=\r\n5'
//        test: skip-2
const hexChars = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F']
const RFC2045Encode1IN = / \r\n|\r\n|[^!-<>-~ ]/gm
const RFC2045Encode1OUT = function (sMatch) {
// Encode space before CRLF sequence to prevent spaces from being stripped
// Keep hard line breaks intact; CRLF sequences
if (sMatch.length > 1) {
return sMatch.replace(' ', '=20')
    }
// Encode matching character
const chr = sMatch.charCodeAt(0)
return'=' + hexChars[((chr >>> 4) & 15)] + hexChars[(chr & 15)]
  }
// Split lines to 75 characters; the reason it's 75 and not 76 is because softline breaks are
// preceeded by an equal sign; which would be the 76th character. However, if the last line/string
// was exactly 76 characters, then a softline would not be needed. PHP currently softbreaks
// anyway; so this function replicates PHP.
const RFC2045Encode2IN = /.{1,72}(?!\r\n)[^=]{0,3}/g
const RFC2045Encode2OUT = function (sMatch) {
if (sMatch.substr(sMatch.length - 2) === '\r\n') {
return sMatch
    }
return sMatch + '=\r\n'
  }
  str = str
    .replace(RFC2045Encode1IN, RFC2045Encode1OUT)
    .replace(RFC2045Encode2IN, RFC2045Encode2OUT)
// Strip last softline break
return str.substr(0, str.length - 3)
}