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match-token build status

Given a string and a position, it finds the position of the token matching the one at the given position.

var matchToken = require('match-token');
matchToken('{1}', 0) // -> 2 
matchToken('{1}', 2) // -> 0 
//          012345678901234 
matchToken('var foo = "bar"', 10) // -> 14 (quotes) 
matchToken('{{1}}', 0) // -> 4 (outer brace) 
matchToken('{{1}}', 1) // -> 3 (inner brace) 


npm i match-token


Matches the following tokens in a given string.

  • { with } and vice versa
  • ( with ) and vice versa
  • [ with ] and vice versa
  • quotes ' and "

Returns position of match in the string or -1 if it was either not found or the the inputs were invalid (i.e. the string was null or undefined or the index was out of range).


Not meant to be perfect, i.e. does no code parsing in order to be able to handle incomplete code.

Simply counts opening vs. closing tokens and therefore does nothing special if a token appears in a string for instance.

//          0123456789  
matchToken('{ a: "}" }', 0) // -> 6 (although it is in a string) 

In order to disambiguate between quotes, i.e., when not sure if given quote is the opener or close, it uses the match that puts the least distance between opening an closing quotes.