[
[
{name: 'Petr', age: 25},
{name: 'Petr', age: 25}
],
[
{name: 'Petr', age: 25},
{name: 'Petr', age: 25}
]
]
const result = arr.flat();
// или
const result = Array.prototype.concat.apply([], arr);
// или
const result = arr.reduce((acc, n) => (acc.push(...n), acc), []);
// или
const result = [];
for (const n of arr) {
for (const m of n) {
result[result.length] = m;
}
}