Run results for: JS array chunk

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:77.0) Gecko/20100101 Firefox/77.0

Browser: Firefox 77

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
1	8911817.0 Ops/sec
2	7120195.0 Ops/sec
3	2930822.0 Ops/sec
4	8805713.0 Ops/sec
5	3376163.0 Ops/sec
6	3672535.0 Ops/sec
7	2244023.0 Ops/sec
8	8594723.0 Ops/sec
9	2988483.0 Ops/sec

Script Preparation code:

function chunk1(xs, n) {
  return xs.reduce(function(o, x, i) {
    o[Math.floor(i / n)].push(x);
    return o;
  }, Array(Math.ceil(xs.length / n)).fill([]));
}

function chunk2(xs, n) {
  return (xs.length <= n) ? [xs] : [
    xs.slice(0, n),
    ...chunk2(xs.slice(n), n)
  ]
}

function chunk3(array, size) {
  //declaring variable 'chunked' as an empty array
  let chunked = []

  //looping through the array until it has been entirely "manipulated" or split into our subarrays
  while (array.length > 0) {
    //taking the spliced segments completely out of our original array
    //pushing these subarrays into our new "chunked" array
    chunked.push(array.splice(0, size))
  }
  //returning the new array of subarrays
  return chunked
}

function chunk4(array, size) {
  //declaring variable 'chunked' as an empty array
  let chunked = []

  //setting our start point for our while loop at index 0
  let i = 0;
  //looping through the array until we have reached the final index
  while (i < array.length) {
    //push the sliced subarray of length 'size' into our new 'chunked' array
    chunked.push(array.slice(i, i + size))
    //increment by the size as to avoid duplicates
    i += size;
  }
  //return the array of subarrays
  return chunked
}

function chunk5(array, size) {
  //declaring variable 'chunked' as an empty array
  let chunked = [];

  //for loop iterating through every element of our input array
  for (let ele of array) {
    //declaring variable 'last' as the last index of our 'chunked' array
    const last = chunked[chunked.length - 1];

    //checking if last is undefined or if the last subarray is equal to the size
    if (!last || last.length === size) {
      //then we push the element to be a new subarray in 'chunked'
      chunked.push([ele])
    } else {
      //if not, then we add the element to the 'last' subarray
      last.push(ele)
    }
  }
  //return the array of subarrays
  return chunked
}

function chunk6(array, size) {
  const chunked_arr = [];
  for (let i = 0; i < array.length; i++) {
    const last = chunked_arr[chunked_arr.length - 1];
    if (!last || last.length === size) {
      chunked_arr.push([array[i]]);
    } else {
      last.push(array[i]);
    }
  }
  return chunked_arr;
}

function chunk7(array, size) {
  const chunked_arr = [];
  let copied = [...array]; // ES6 destructuring
  const numOfChild = Math.ceil(copied.length / size); // Round up to the nearest integer
  for (let i = 0; i < numOfChild; i++) {
    chunked_arr.push(copied.splice(0, size));
  }
  return chunked_arr;
}

function chunk8(array, size) {
  const chunked_arr = [];
  let index = 0;
  while (index < array.length) {
    chunked_arr.push(array.slice(index, size + index));
    index += size;
  }
  return chunked_arr;
}

function chunk9(array, size) {
  if (!array) return [];
  const firstChunk = array.slice(0, size); // create the first chunk of the given array
  if (!firstChunk.length) {
    return array; // this is the base case to terminal the recursive
  }
  return [firstChunk].concat(chunk9(array.slice(size, array.length), size));
}

Tests:

1
chunk1([1, 2, 3, 4], 2);
2
chunk2([1, 2, 3, 4], 2);
3
chunk3([1, 2, 3, 4], 2);
4
chunk4([1, 2, 3, 4], 2);
5
chunk5([1, 2, 3, 4], 2);
6
chunk6([1, 2, 3, 4], 2);
7
chunk7([1, 2, 3, 4], 2);
8
chunk8([1, 2, 3, 4], 2);
9
chunk9([1, 2, 3, 4], 2);