Example 1: javascript array flatten
// flat(depth),
// depth is optional: how deep a nested array structure
// should be flattened.
// default value of depth is 1
const arr1 = [1, 2, [3, 4]];
arr1.flat();
// [1, 2, 3, 4]
const arr2 = [1, 2, [3, 4, [5, 6]]];
arr2.flat();
// [1, 2, 3, 4, [5, 6]]
const arr3 = [1, 2, [3, 4, [5, 6]]];
arr3.flat(2);
// [1, 2, 3, 4, 5, 6]
const arr4 = [1, 2, [3, 4, [5, 6, [7, 8, [9, 10]]]]];
arr4.flat(Infinity);
// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Example 2: flatten an array in javascript
function flatten(arr) {
const result = []
arr.forEach((i) => {
if (Array.isArray(i)) {
result.push(...flatten(i))
} else {
result.push(i)
}
})
return result
}
// Usage
const nested = [1, 2, 3, [4, 5, [6, 7], 8, 9]]
flatten(nested) // [1, 2, 3, 4, 5, 6, 7, 8, 9]