Array.prototype.flat()
The flat() method of Array instances creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.
Syntax
flat()
flat(depth)Parameters
depth(optional)- The depth level specifying how deep a nested array structure should be flattened. Defaults to
1.
Return value
A new array with the sub-array elements concatenated into it.
Examples
Flattening nested arrays
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]