SimilaryUtils Library, compares two strings and based on the Sørensen–Dice coefficient it calculates the % of similarity between both strings.

SimilarityUtils.js

/**
  * SimilarityUtils Library
  * Compares two strings and based on the Sørensen–Dice coefficient it calculates the % of similarity between both strings.
  *
  * Usage:
  * SimilarityUtils.compare("string","stringg").toFixed(2);
***/
var SimilarityUtils = {
  /**
    *
    * Get Bigram of a word, e.g. "String", translates into: ["st","tr","ri","in","ng"]
    *
  ***/
  bigramSet : function(string1){
    var arr = [];
    if(string1.length > 1){
      for (var index = 1; index < string1.length; index++) {
          arr.push(string1.substring(index -1, index + 1));
      }
   }
   else{
     arr.push(string1);
   }
   return arr;
 },
 /**
   *
   * Get Number of direct index matches in two arrays
   *
 ***/
 numElementMatch : function(arr1, arr2){
   var numOfMatches = 0;
   var short = (arr1.length < arr2.length)? arr1 : arr2;

   for(var index = 0; index < short.length; index++){
     if(arr1[index] == arr2[index]){
       numOfMatches++;
     }
   }

   return numOfMatches;
 },
 /**
   *
   * Calculate percentage of similarity in two words based on the Sørensen–Dice coefficient
   *
 ***/
 compare : function(string1, string2){
   var arr1 = this.bigramSet(string1);
   var arr2 = this.bigramSet(string2);
   var numOfMatches = this.numElementMatch(arr1,arr2);

   return (2*numOfMatches) / (arr1.length + arr2.length);
 }


}