코드 :

function find_FirstNotRepeatedChar(str) {
  var arra1 = str.split('');
  var result = '';
  var ctr = 0;
 
  for (var x = 0; x < arra1.length; x++) {
    ctr = 0;
 
    for (var y = 0; y < arra1.length; y++) 
    {
      if (arra1[x] === arra1[y]) {
        ctr+= 1;
      }
    }
 
    if (ctr < 2) {
      result = arra1[x];
      break;
    }
  }
  return result;
}
console.log(find_FirstNotRepeatedChar('abacddbec'));

결과 :

e