PHP's quoted_printable_encode in TypeScript

How to use

Install via yarn add locutus and import: import { quoted_printable_encode } from 'locutus/php/strings/quoted_printable_encode'.

Or with CommonJS: const { quoted_printable_encode } = require('locutus/php/strings/quoted_printable_encode')

Use a bundler that supports tree-shaking so you only ship the functions you actually use. Vite, webpack, Rollup, and Parcel all handle this. For server-side use this is less of a concern.

Examples

These examples are extracted from test cases that automatically verify our functions against their native counterparts.

#	code	expected result
1	quoted_printable_encode('a=b=c')	'a=3Db=3Dc'
2	quoted_printable_encode('abc \r\n123 \r\n')	'abc =20\r\n123 =20\r\n'
3	quoted_printable_encode('0123456789012345678901234567890123456789012345678901234567890123456789012345')	'012345678901234567890123456789012345678901234567890123456789012345678901234=\r\n5'

Here's what our current TypeScript equivalent to PHP's quoted_printable_encode looks like.

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export function quoted_printable_encode(str: string): string {
  //      discuss at: https://locutus.io/php/quoted_printable_encode/
  // parity verified: PHP 8.3
  //     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'

  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: string): string {
    // 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: string): string {
    if (sMatch.endsWith('\r\n')) {
      return sMatch
    }
    return sMatch + '=\r\n'
  }

  str = str.replace(RFC2045Encode1IN, RFC2045Encode1OUT).replace(RFC2045Encode2IN, RFC2045Encode2OUT)

  // Strip last softline break (only if it's a soft break =\r\n, not a hard break \r\n)
  if (str.endsWith('=\r\n')) {
    return str.slice(0, -3)
  }
  return str
}

export function quoted_printable_encode(str) {
  //      discuss at: https://locutus.io/php/quoted_printable_encode/
  // parity verified: PHP 8.3
  //     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'

  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.endsWith('\r\n')) {
      return sMatch
    }
    return sMatch + '=\r\n'
  }

  str = str.replace(RFC2045Encode1IN, RFC2045Encode1OUT).replace(RFC2045Encode2IN, RFC2045Encode2OUT)

  // Strip last softline break (only if it's a soft break =\r\n, not a hard break \r\n)
  if (str.endsWith('=\r\n')) {
    return str.slice(0, -3)
  }
  return str
}

Improve this function

Locutus is a community effort following The McDonald's Theory: we ship first iterations, hoping others will improve them. If you see something that could be better, we'd love your contribution.

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