​

function reverse(stack, character){

  if(character == " "){

    var res = "";

    while(!stack.empty()){

      res += stack.pop();

    }

    res += " ";

    return res;

  } else {

    stack.push(character);

    return "";

  }

}

​

function reverseSentence(s){

  var n = s.length;

  var stack = new ArrayStack();

  stack.create();

  var res = "";

  for(var i=0; i<n; i++){

    res += reverse(stack, s[i]);

  }

  while(!stack.empty()){

    res += stack.pop();

  }

  return res;

}

​

console.log(reverseSentence("dreh um"));

​