Split jsonarray into chunk arrays into another array

The following snippet splits arrays into chunks by size.

Array.prototype.filter() is used to omit unwanted elements (even numbers) from the input array.

Array.prototype.slice and a for statement are combined to create chunks without mutating the original input array.

Leftovers are included as a final chunk in the output, when relevant.

// Input.
const input = [1, 2, 3, 4, 5, 6, 7, 8, 9].filter(x => x % 2)

// Chunk.
const chunk = (array, size) => {
  let output = []
  let i = 0
  const max = array.length + (array.length % size) + 1
  for (let j = size; j < max; j += size) {
    output.push(array.slice(i, j))
    i = j
  }
  return output
}

// Output / Proof.
console.log('chunk size: 1', chunk(input, 1))
console.log('chunk size: 3', chunk(input, 3))
console.log('chunk size: 5', chunk(input, 5))

You can split array into given number of chunks

split(arr, n) {
        var res = [];
        while (arr.length) {
            res.push(arr.splice(0, n));
        }
        return res;
    }

Usage

 var arrayFregments = split(myArray, 3); //no of chunks
 var requests = arrayFregments.reduce((promiseChain, item) => {
            return promiseChain.then(() => new Promise((resolve) => {
                 asyncFunction(item, resolve); //some async function
            }));
        }, Promise.resolve());

 requests.then(() => {
               // after requests has been completed.
            });

Update

If you want to eliminate empty data object then you can use filter

mainList = mainList.filter(function(item){
        return item.title.trim().length>0 && item.description.trim().length>0

});
console.log(mainList)

Example - http://jsfiddle.net/zj1pe7q3/3/

Try something like that:

const chucnk = (array, chunckSize) =>
  array.reduce(
    (a, b, i, g) =>
      !(i % chunckSize) ? a.concat([g.slice(i, i + chunckSize)]) : a,
    []
  );

const array = [{
  title: "asd",
  description: "asd"
}, {
  title: "asz",
  description: "sd"
}, {
  title: "ws",
  description: "sd"
}, {
  title: "re",
  description: "sd"
}, {
  title: "32",
  description: "xxs"
}, {
  title: "xxc",
  description: "11"
}]

chunck(array,3);

// Chunk a single array into multiple arrays, each containing `count` or fewer
  // items.
function chunk(array, count) {
    if (count == null || count < 1) return [];
    var result = [];
    var i = 0, length = array.length;
    while (i < length) {
      result.push(Array.prototype.slice.call(array, i, i += count));
    }
    return result;
  };

Usage:

var newList = chunk(mainList, 2);

Demo Fiddle

OR

You can use chunk of underscore or lodash

var mainList = [
  {
    "title": "asd",
    "description": "asd"
  },
  {
    "title": "asz",
    "description": "sd"
  },
  {
    "title": "ws",
    "description": "sd"
  },
  {
    "title": "re",
    "description": "sd"
  },
  {
    "title": "32",
    "description": "xxs"
  },
  {
    "title": "xxc",
    "description": "11"
  }
];

var newList = _.chunk(mainList, 2);

Output:

[
  [
    {
      "title": "asd",
      "description": "asd"
    },
    {
      "title": "asz",
      "description": "sd"
    }
  ],
  [
    {
      "title": "ws",
      "description": "sd"
    },
    {
      "title": "re",
      "description": "sd"
    }
  ],
  [
    {
      "title": "32",
      "description": "xxs"
    },
    {
      "title": "xxc",
      "description": "11"
    }
  ]
]