JavaScript で重複削除のテストコード

duplicate-removal.js

let array = [...Array(50)].map(_ => Math.floor(Math.random() * 20));

let a = array.filter(function (x, i, self) {
  return self.indexOf(x) === i;
});
let b = Array.from(new Set(array));
console.log(a, b);

let loopCount = 1000000;

console.time("filter");
for (let i = 0; i < loopCount; ++i) {
  let a = array.filter(function (x, i, self) {
    return self.indexOf(x) === i;
  });
}
console.timeEnd("filter");

console.time("set");
for (let i = 0; i < loopCount; ++i) {
  let a = Array.from(new Set(array));
}
console.timeEnd("set");

result.txt

$ node duplicate-removal.js
[
   3,  9, 17, 11, 16, 14, 4,
   6,  2, 12, 15,  7, 18, 1,
  13, 19, 10,  8,  5
] [
   3,  9, 17, 11, 16, 14, 4,
   6,  2, 12, 15,  7, 18, 1,
  13, 19, 10,  8,  5
]
filter: 1184.350ms
set: 1253.351ms