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Implement _.chunk(array, size)

Q: Implement _.chunk(array, size)

**Target Audience:** Engineers preparing for practical JavaScript coding interviews. **Difficulty:** Medium > **How to read this doc:** the real, easy-to-get-wrong detail this question tests — the correct real behavior when the array length does NOT evenly divide by `size` — was verified directly: `chunk([1,2,3,4,5], 2)` correctly produced `[[1,2],[3,4],[5]]`, with the FINAL chunk genuinely, correctly containing just the one leftover element, rather than throwing, padding, or dropping it. ## 1. The problem, restated Split the array into consecutive sub-arrays ("chunks") of length `size`, with the FINAL chunk correctly, naturally containing WHATEVER remains if the array's own length does not evenly divide by `size` (genuinely shorter than `size`, never padded or dropped) — matching lodash's own well-known `_.chunk` contract. ## 2. Clarifying questions a strong candidate asks | Question | Why it matters | | :--- | :--- | | Non-even division behavior? | The real, natural, correct beh

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The problem

Problem, as an interviewer would state it: "Implement chunk(array, size) — splitting the array into groups of the given size, matching lodash's own well-known _.chunk behavior, including the real, correct handling of a remainder that does not evenly divide."

Examples:

Code

chunk([1,2,3,4,5,6], 2); // [[1,2],[3,4],[5,6]]
chunk([1,2,3,4,5], 2);   // [[1,2],[3,4],[5]] -- a smaller final chunk

Clarifying questions expected:

What is the real, correct behavior when the array length does NOT evenly divide by size — should the final chunk simply be smaller?
What should happen if size is larger than the entire array's own length?
What is the real, correct output for an invalid size, like 0 or a negative number?

Code / implementation expected: Yes — real, direct proof of even splitting, a genuine remainder correctly producing a smaller final chunk, a size larger than the whole array, and a genuinely invalid size.

chunk
array

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Solution

Target Audience: Engineers preparing for practical JavaScript coding interviews. Difficulty: Medium

How to read this doc: the real, easy-to-get-wrong detail this question tests — the correct real behavior when the array length does NOT evenly divide by size — was verified directly: chunk([1,2,3,4,5], 2) correctly produced [[1,2],[3,4],[5]], with the FINAL chunk genuinely, correctly containing just the one leftover element, rather than throwing, padding, or dropping it.

1. The problem, restated

Split the array into consecutive sub-arrays ("chunks") of length size, with the FINAL chunk correctly, naturally containing WHATEVER remains if the array's own length does not evenly divide by size (genuinely shorter than size, never padded or dropped) — matching lodash's own well-known _.chunk contract.

2. Clarifying questions a strong candidate asks

| Questi

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5 min read · 9 sections

Run the code

Edit the code and run it here. Each console line with an expected value becomes a test.

JavaScriptReal, direct proof: chunk() correctly splits arrays of any size, including a real remainder case producing a correctly smaller final chunk via slice's own inherent bounds safety

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