title: Find the characters in a string which are not duplicated
body: <p>I have to make a function in JavaScript that removes all duplicated letters in a string. So far I've been able to do this: If I have the word "anaconda" it shows me as a result "anaconda" when it should show "cod". Here is my code:</p>
  
  <pre><code>function find_unique_characters( string ){
      var unique='';
      for(var i=0; i&lt;string.length; i++){
          if(unique.indexOf(string[i])==-1){
              unique += string[i];
          }
      }
      return unique;
  }
  console.log(find_unique_characters('baraban'));
  </code></pre>