[рони]

querubin ,

function str_pack(arr) {
  return arr.join('').replace(/1+/g, a => a.length)
}
console.log(str_pack([1,1,'Q',1,'R']));
console.log(str_pack([1,1,1,'Q',1,1,'R',1]));
console.log(str_pack([1,1,'N','W',1,1,1,'Q']));