balanced-match

balanced-match

Match balanced string pairs, like { and } or <b> and </b>. Supports regular expressions as well!

Example

Get the first matching pair of braces:

import { balanced } from 'balanced-match'

console.log(balanced('{', '}', 'pre{in{nested}}post'))
console.log(balanced('{', '}', 'pre{first}between{second}post'))
console.log(
  balanced(/\s+\{\s+/, /\s+\}\s+/, 'pre  {   in{nest}   }  post'),
)

The matches are:

$ node example.js
{ start: 3, end: 14, pre: 'pre', body: 'in{nested}', post: 'post' }
{ start: 3,
  end: 9,
  pre: 'pre',
  body: 'first',
  post: 'between{second}post' }
{ start: 3, end: 17, pre: 'pre', body: 'in{nest}', post: 'post' }

API

const m = balanced(a, b, str)

For the first non-nested matching pair of a and b in str, return an object with those keys:

• start the index of the first match of a
• end the index of the matching b
• pre the preamble, a and b not included
• body the match, a and b not included
• post the postscript, a and b not included

If there's no match, undefined will be returned.

If the str contains more a than b / there are unmatched pairs, the first match that was closed will be used. For example, {{a} will match ['{', 'a', ''] and {a}} will match ['', 'a', '}'].

const r = balanced.range(a, b, str)

For the first non-nested matching pair of a and b in str, return an array with indexes: [ <a index>, <b index> ].

If there's no match, undefined will be returned.

If the str contains more a than b / there are unmatched pairs, the first match that was closed will be used. For example, {{a} will match [ 1, 3 ] and {a}} will match [0, 2].

Similar packages

Other packages similar to balanced-match

brace-expansion

The brace-expansion package is similar to balanced-match in that it deals with matching patterns within strings, specifically brace expansion patterns. It is more specialized for brace pattern expansion and does not provide the generic balanced string matching capabilities of balanced-match.