mismatch

mismatch

mismatch is a JavaScript package to return captured groups of a regular expression as objects in an array.

yarn add mismatch

Table Of Contents

• Table Of Contents
• API
  • mismatch(re: RegExp, string: string, keys: string[], addPosition?: boolean)
• Copyright

API

The package is available by importing its default function:

import mismatch from 'mismatch'

mismatch(
  re: RegExp,
  string: string,
  keys: string[],
  addPosition?: boolean,
): void

The function will attempt to find all matches for a given regular expression in a string using .replace() method, construct an object consisting of captured groups based on supplied keys, and return those objects as an array. It has an advantage over iterating over while(RegExp.exec(string)) pattern because it does not modify the regular expression's lastIndex property.

/* yarn example/ */
import mismatch from 'mismatch'

const re = /(\w+)="(.+?)"/g
const string = `
<script
  crossorigin="anonymous"
  src="https://static.npmjs.com/commons.js"
  integrity="sha512-example/rhb92Zdom+ix+AYtqZ7C1DlLKEA=="
></script>
`
const keys = ['attribute', 'value']
const res = mismatch(re, string, keys)
console.log(JSON.stringify(res, null, 2))

[
  {
    "attribute": "crossorigin",
    "value": "anonymous"
  },
  {
    "attribute": "src",
    "value": "https://static.npmjs.com/commons.js"
  },
  {
    "attribute": "integrity",
    "value": "sha512-example/rhb92Zdom+ix+AYtqZ7C1DlLKEA=="
  }
]

If an optional capturing group was not found, its key will not be included as part of the object. Also, if there are more captured groups than keys, they will also not be included.

/* yarn example/extra.js */
import mismatch from 'mismatch'

const re = /(?: type="(.+?)")?\s+crossorigin="(.+?)"\s+src="(.+?)"/g
const string = `
<script
  crossorigin="anonymous"
  src="https://static.npmjs.com/commons.js"
  integrity="sha512-example/rhb92Zdom+ix+AYtqZ7C1DlLKEA=="
></script>
`
const keys = ['type', 'crossorigin']
const res = mismatch(re, string, keys)
console.log(JSON.stringify(res, null, 2))

[
  {
    "crossorigin": "anonymous"
  }
]

To additionally add the positions at which the matches was found, the last argument, addPositions should be set to true.

/* yarn example/ */
import mismatch from 'mismatch'

const re = /(\w+)="(.+?)"/g
const string = `
<script
  crossorigin="anonymous"
  src="https://static.npmjs.com/commons.js"
  integrity="sha512-example/rhb92Zdom+ix+AYtqZ7C1DlLKEA=="
></script>
`
const keys = ['attribute', 'value']
const res = mismatch(re, string, keys, true)
console.log(JSON.stringify(res, null, 2))

[
  {
    "position": 11,
    "attribute": "crossorigin",
    "value": "anonymous"
  },
  {
    "position": 37,
    "attribute": "src",
    "value": "https://static.npmjs.com/commons.js"
  },
  {
    "position": 81,
    "attribute": "integrity",
    "value": "sha512-example/rhb92Zdom+ix+AYtqZ7C1DlLKEA=="
  }
]

Copyright

	© Art Deco 2019		Tech Nation Visa Sucks

Changelog

1.2.0

• [feature] Add the addPositions argument to return the positions of matches.

8 April 2019