npm package

readJsonRegExp

Read jsonRegExp string and return a RegExp for it

Implements jsonRegExp, e.g. reads in

'a+b'

and returns

/a\+b/

or

'`(`^`|/`).git`(`/`|`$`)'

and returns

/(^|\/)\.git(\/|$)/

hh lohmann <hh.lohmann@gmail.com>

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Changelog

Last 3 changes - see CHANGELOG file for full list and details

• (1.0.0) v1.0.0

Synopsis

  import { readJsonRegExp } from 'read-jsonregexp'

Parameters

jsonRegExp

String: The string to interpret as jsonRegExp

Settings

none

Returns

RegExp represention for the evaluated jsonRegExp

Examples

• jsonRegExp without any RegExp

  const myString='k8s'
  console.log(readJsonRegExp(myString)) // /k8s/
  

• jsonRegExp with RegExp for character range with RegExp metacharacters []

  const myString='k`[0-9`]s'
  console.log(readJsonRegExp(myString)) // /k[0-9]s/
  

• jsonRegExp with literal []

  const myString='k[number]s'
  console.log(readJsonRegExp(myString)) // /k\[number\]s/
  

• jsonRegExp with RegExp for character range including literal ^

  const myString='k`[^8`]s'
  console.log(readJsonRegExp(myString)) // /k[\^8]s/
  

• jsonRegExp with RegExp for character range negated by RegExp metacharacter ^

  const myString='k`[`^8`]s'
  console.log(readJsonRegExp(myString)) // /k[^8]s/
  

• jsonRegExp with RegExp with flag

  const myString='k`.s`/i'
  console.log(readJsonRegExp(myString)) // /k.s/i
  

  • if the part after `/ contains anything that is not a valid flag (including multiple usage of the same flag) it will be given back as a literal sequence with backtick and slash, e.g.

    const myString='k`.s`/noflags'
    console.log(readJsonRegExp(myString)) // /k.s`\/noflags/
    

    This substitutes (for various reasons) an error message like “invalid backtick sequence: sequence”

• jsonRegExp with literal backtick (= backtick quoted by backtick)

  const myString='k``8s'
  console.log(readJsonRegExp(myString)) // /k`8s/
  

Installation

Pick for your preferred package manager:

  npm i read-jsonregexp

  pnpm i read-jsonregexp

  bun i read-jsonregexp

  # For Yarn you should double check docs for your and / or
  # current Yarn version, newer versions do not treat `i package_name`
  # as an alias for `add ...` and exclude global installations
  yarn add read-jsonregexp

Details

• Expects a single string as input, not a JSON object or file (i.e. a corresponding JSON has to be read in / evaluated by other means, e.g. a process that uses readJsonRegExp to transform a JSON into a JavaScript object that allows RegExps as values)
• Uses JavaScript’s RegExp to evaluate and transform jsonRegExps
• Handles the RegExp metacharacters recognized by JavaScript’s RegExp:

  ^ $ \ * + ? { } ( ) [ ] |
  

Tests

• Code tests to be run with Node.js / Bun available in Source Code

Source Code

• GitHub: https://github.com/hh-lohmann/read-jsonregexp

License

• MIT (see LICENSE.txt)

References

hh lohmann: jsonRegExp

• Store RegExp as JSON string without an unreadable mess of escaping / quoting metacharacters
• https://hh-lohmann.github.io/json-regexp/

MDN: RegExp

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp

MDN: Regular Expressions: Flags

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions#advanced_searching_with_flags

MDN: Syntax characters in regular expressions

• = metacharacters
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Literal_character#:~:text=syntax%20characters%20in%20regular%20expressions

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