["first", "second", "third"]{answer1: "first", answer2: "second", answer3: "third"} и так сколько этих самих элементов в массиве.
const key = 'answer';.const obj = Object.fromEntries(arr.map((n, i) => [ `${key}${i + 1}`, n ]));const obj = arr.reduce((acc, n, i) => (acc[key + ++i] = n, acc), {});const obj = {};
for (const [ i, n ] of arr.entries()) {
obj[key.concat(-~i)] = n;
}const obj = (function get(arr) {
const i = arr.length;
const n = arr.pop();
return i
? { ...get(arr), [[ key, i ].join``]: n }
: {};
})([...arr]);