const result = [];
for (const n of elements) {
if (!used.some(m => m.id === n.id)) {
result.push(n);
}
}
или
const result = elements.filter(function(n) {
return !this.has(n.id);
}, new Set(used.map(n => n.id)));
или
const result = (function get(ids, i, n = elements[i]) {
return n
? [].concat(ids.includes(n.id) ? [] : n, get(ids, -~i))
: [];
})(used.map(n => n.id), 0);
или
const result = Object.values(used.reduce(
(acc, n) => (delete acc[n.id], acc),
elements.reduce((acc, n) => (acc[n.id] = n, acc), {})
));
или
const result = [...used.reduce(
(acc, n) => (acc.delete(n.id), acc),
new Map(elements.map(n => [ n.id, n ]))
).values()];