locutus/esm/elixir/Enum/chunk_every.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

export function chunk_every(values, count, step = count, leftover = []) {
    //      discuss at: https://locutus.io/elixir/chunk_every/
    // parity verified: Elixir 1.18
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Mirrors Elixir Enum.chunk_every/4 semantics with count, step and optional leftover padding.
    //       example 1: chunk_every([1, 2, 3, 4, 5], 2)
    //       returns 1: [[1, 2], [3, 4], [5]]
    //       example 2: chunk_every([1, 2, 3, 4, 5], 2, 2, [])
    //       returns 2: [[1, 2], [3, 4], [5]]
    //       example 3: chunk_every([1, 2, 3, 4, 5], 3, 3, [0, 0])
    //       returns 3: [[1, 2, 3], [4, 5, 0]]
    if (!Array.isArray(values)) {
        return [];
    }
    const width = Math.trunc(Number(count));
    const stride = Math.trunc(Number(step));
    if (!Number.isFinite(width) || width <= 0) {
        throw new RangeError('chunk_every(): count must be a positive integer');
    }
    if (!Number.isFinite(stride) || stride <= 0) {
        throw new RangeError('chunk_every(): step must be a positive integer');
    }
    const pad = Array.isArray(leftover) ? leftover : [];
    const out = [];
    for (let i = 0; i < values.length; i += stride) {
        const chunk = values.slice(i, i + width);
        if (chunk.length === width) {
            out.push(chunk);
            continue;
        }
        if (chunk.length === 0) {
            continue;
        }
        const padded = [...chunk, ...pad].slice(0, width);
        if (padded.length > 0) {
            out.push(padded);
        }
    }
    return out;
}