assertions.js

var uk = createFuzzyScorer('United Kingdom');
var us = createFuzzyScorer('United States');

console.log([
  uk('United') > uk('uk'),
  uk('nited') > uk('ingdom'),
  uk('united kingdom') > uk('united kingdo'),
  uk('united dom') < uk('united kin'),
  uk('knited k') > uk('dom'),
  uk('_united_') < uk('united'),
  uk('United') == us('United')
]);

createFuzzyScorer.js

function createFuzzyScorer(text) {
  
  var UNIVERSAL_MAX = 1e9;
  
  var matcher = makeFuzzyRegex(text);
  
  return function(query) {
    var match = matcher.exec(query);
    
    if (!match) return 0;
    
    var captures = match.slice(1);
    var score = 0; console.log(captures);

    for (var i = 0, l = captures.length; i < l; i += 3) {
      var relevancyOfCharacter = Math.pow(i + 1, -2);
      if (captures[i]) score -= relevancyOfCharacter * 0.1;
      if (captures[i+1]) score += relevancyOfCharacter * 1;
      if (captures[i+2]) score -= relevancyOfCharacter * 0.1;
    }

    return score;
  };
  
  function makeFuzzyRegex(string) {

    if (!string) { return /^$/; }

    // Escape any potential special characters:
    var cleansed = string.replace(/\W/g, '\\$&');

    return RegExp(
      '^' +
        cleansed.replace(
          // Find every escaped and non-escaped char:
          /(\\?.)/g,
          // Replace with fuzzy character matcher:
          '(?:(^.)?($1)(.??))?'
        ) +
      '$',
      'i'
    );
  }
}

may it be better, if you code w/o slice and start the for from 1, at makeFuzzyRegex function?