12345678910111213141516171819202122232425262728293031323334353637383940414243444546
/** * Split an array into chunks of a specified size. This function * has the same behavior as [PHP's array_chunk](http://php.net/manual/en/function.array-chunk.php) * function, and thus will insert smaller-sized chunks at the end if * the input size is not divisible by the chunk size. * * `x` is expected to be an array, and `chunkSize` a number. * The `x` array can contain any kind of data. * * @param {Array} x a sample * @param {number} chunkSize size of each output array. must be a positive integer * @returns {Array<Array>} a chunked array * @throws {Error} if chunk size is less than 1 or not an integer * @example * chunk([1, 2, 3, 4, 5, 6], 2); * // => [[1, 2], [3, 4], [5, 6]] */function chunk(x, chunkSize) {    // a list of result chunks, as arrays in an array    const output = [];
    // `chunkSize` must be zero or higher - otherwise the loop below,    // in which we call `start += chunkSize`, will loop infinitely.    // So, we'll detect and throw in that case to indicate    // invalid input.    if (chunkSize < 1) {        throw new Error("chunk size must be a positive number");    }
    if (Math.floor(chunkSize) !== chunkSize) {        throw new Error("chunk size must be an integer");    }
    // `start` is the index at which `.slice` will start selecting    // new array elements    for (let start = 0; start < x.length; start += chunkSize) {        // for each chunk, slice that part of the array and add it        // to the output. The `.slice` function does not change        // the original array.        output.push(x.slice(start, start + chunkSize));    }    return output;}
export default chunk;