:

• , .
• , , .

function unique(arr) {
  let result = [];

  for (let str of arr) {
    if (!result.includes(str)) {
      result.push(str);
    }
  }

  return result;
}

let strings = ["", "", "", "",
  "", "", "", "", ":-O"
];

alert( unique(strings) ); // , , :-O

, .

result.includes(str) result str, .

, result 100 str, result 100 . result , , 10000 , 10000 .

, JavaScript , 10000 .

arr for.

, arr.length 10000, 10000*10000 = 100 . .

.

Map Set , .

.