Flatten One Level

Working With Arraysmedium

Course · Section 11: Working With Arrays · Lecture 149: Simple Array Methods

Implement `flatten(arr)` flattening one level of nesting.

Input: flatten([1,[2,3],4,[5]])

Output: [1,2,3,4,5]

Input: flatten([[1],[2]])

Output: [1,2]

+ 1 hidden test run on Submit.

Common pitfalls

flat() also works but flattens deeper if given a depth; one level is the goal here.

Approach & explanation (try first)

Spreading the array into [].concat merges nested arrays exactly one level deep.

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