duplicatecount.ts

function duplicateCounta(text : string){
  return text
      .toLowerCase()
      .split('')
      .reduce(function(a, l) {
        a[l] = a[l] ? a[l]+1 : 1;
        if(a[l] === 2) a.count++;
        return a;
      }, {count:0}).count;
}

// i solved this one in a similiar way using reduce, but this other solution from a code warrior is really good, had to save it.