const array = [1, 2, 7, 3, 3, 4, 5, 6, 7, 8, 7];
function ggwp(arr) {
const uniq = [];
return arr.reduce((acc, curr) => {
if (!uniq.includes(curr)) {
uniq.push(curr);
return acc;
} else {
return acc.concat(curr);
}
}, []);
}
console.info("--> ggwp 4444", ggwp(array));