flat a array code example

Example 1: array flatten

const arr = [1, 2, [3, 4]];

// To flat single level array
arr.flat();
// is equivalent to
arr.reduce((acc, val) => acc.concat(val), []);
// [1, 2, 3, 4]

// or with decomposition syntax
const flattened = arr => [].concat(...arr);

Example 2: flatten nested array javascript

const arr2 = [1, 2, [3, 4, [5, 6]]];
arr2.flat();