checkBrackets.js

'use strict';
var _ = require('lodash');

// allow for parenthesis square brackets, curly braces

function check(input) {
  var tokens = [[/\[/,/\]/],[/\{/,/\}/],[/\(/, /\)/]];
  
  /*
    search for the token pair on a string, starting with input
  */
  var searchInput = function(pair) {
    return searchPair(pair,input);
  };

  /*
    search for the token pair on a string, recursively
  */
  var searchPair = function(pair, str) {
    if (str === '') return true; // no more string to search, return true

    var matchFirst = searchToken(pair[0],str);
    if (matchFirst.length > 0) {
      var matchSecond = searchToken(pair[1],matchFirst);
      if (matchSecond.length == 0) {
        return false;
      }
    }

    // recursively call this function as long as there is more
    return searchPair(pair,matchFirst);
  };

  /*
    search for the given token and return the remaining string after the token
  */
  var searchToken = function(token, str) {
    if (str.search(token) > -1) {
      return str.substring(str.search(token) +1);
    } else {
      return '';
    }
  };

  console.log("Validating input: "+input);

  // _.map(tokens, searchInput) will return us an array
  // with a true or false for each token
  // adding the _.compact is just a way to say if any of the array are false
  // then the whole check is false 
  return _.compact(_.map(tokens, searchInput)).length === tokens.length;
}

console.log(check("sdsf[wer")); // short and false
console.log(check("sdkskdjf(sd[sd]f)sdfs{df(wesdf)sd}fsd(sdfsd(sdfssdf)sdzs)")); // long and good
console.log(check("sdkskdjf(sd[sd]f)sdfs{df(wesdf)sd}fsd(sdfsd(sdfssdf)sd[zs)")); // long and false (at the end, an open [ bracket)

/*  --- my ouput
Sites/viv $ node app.js
Validating input: sdsf[wer
false
Validating input: sdkskdjf(sd[sd]f)sdfs{df(wesdf)sd}fsd(sdfsd(sdfssdf)sdzs)
true
Validating input: sdkskdjf(sd[sd]f)sdfs{df(wesdf)sd}fsd(sdfsd(sdfssdf)sd[zs)
false