ScriptdrillFlatten one level
A JavaScript exercise from Scriptdrill. Solve it with a code editor in your browser that runs your function against example and hidden tests, and it is checked the moment you submit.
The task
Return a new array where items that are arrays are replaced by their contents, one level deep only. Items that are not arrays (numbers, strings, `null`, objects) stay as they are, and deeper arrays stay nested.
What this exercise teaches
Array.isArray is the reliable test: typeof says "object" for arrays, plain objects and null alike, so it would try to spread null. flat() with no argument flattens exactly one level.
A hint if you get stuck
Check each item with `Array.isArray`. Spread arrays into the result and push everything else. The built-in `arr.flat()` does exactly one level too.
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