function differentSymbolsNaive(str) {
     
     // 1. For loop
     var unique= "";
      for(var i = 0; i < str.length; i++)
      {
        if(unique.indexOf(str.charAt(i)) < 0) 
        {
          unique += str.charAt(i);
        }
      }
      //return unique.length;
      
      //2. Using set...
       var stringResult =  String.prototype.concat(...new Set(str)).length
    
     //3. Arrays
     var arrayresult = str.split('').filter(function(item, i, ar){ return ar.indexOf(item) === i; }).join('').length;
    
    // 4.  loadash
   // return _.uniq(str).join('').length; // gives 'abc'
     
     //5. Array prototype...
    var arrayprotoResult =  Array.prototype.map.call(str, 
  (obj,i)=>{
    if(str.indexOf(obj,i+1)==-1 ){
     return obj;
    }
  }
).join("").length;

    //6. While loop
    var len = str.length;
    var coll = [];
    var a=0;
    while(len--)
    {
        if(!coll.includes(str[len]))
        {
            coll.push(str[len]);
        }            
    }
  
    return coll.length;
    
}



/**
* Test Suite 
*/
describe('differentSymbolsNaive()', () => {
    it('returns count of unique characters', () => {
        // arrange
        const str = 'cabca';
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(3);
    });
});