title: How to modify this function to return string instead of int
body: <p>please take a quick look at this function that I have found on the web.</p>
  
  <pre><code>function longestCommonSubstring(string1, string2){
          // init max value
          var longestCommonSubstring = 0;
          // init 2D array with 0
          var table = Array(string1.length);
          for(a = 0; a &lt;= string1.length; a++){
                  table[a] = Array(string2.length);
                  for(b = 0; b &lt;= string2.length; b++){
                          table[a][b] = 0;
                  }
          }
          // fill table
          for(var i = 0; i &lt; string1.length; i++){
                  for(var j = 0; j &lt; string2.length; j++){
                          if(string1[i]==string2[j]){
                                  if(table[i][j] == 0){
                                          table[i+1][j+1] = 1;
                                  } else {
                                          table[i+1][j+1] = table[i][j] + 1;
                                  }
                                  if(table[i+1][j+1] &gt; longestCommonSubstring){
                                          longestCommonSubstring = table[i+1][j+1];
                                  }
                          } else {
                                  table[i+1][j+1] = 0;
                          }
                  }
          }
          return longestCommonSubstring;
  }
  </code></pre>
  
  <p>It returns the length of the longest common substring as an int. Now to my question, is it possible to modify this function, so that it returns the actual string instead of just returning the length of the substring, I'm quite new at programming and thought that just modifying this secetion would help <code>if(string1[i]==string2[j]){ push(string1[i]}</code>, but it isn't that easy, because I don't want every single character that is the same in those 2 strings to be added in that array, only those that are exactly the same.
  Thanks in advance =)</p>