Chunk an array of objects using javascript

Question

I build a function to put array into chunk arrays like:

function conditionalChunk(array, size, rules = {}) {
  let copy = [...array],
      output = [],
      i = 0;

  while (copy.length)
    output.push( copy.splice(0, rules[i++] ?? size) )

  return output
}

const input = [[1,2,3],[4,5,6,7]],
            output = conditionalChunk(input.flat(), 3, { 0: 2, 1: 2 });

// OUTPUT: [[1,2],[3,4],[5,6,7]]

and the chunk is actually pages in my case but I need some more details to put there so now I have:

[{'page_layout': 1, 'theme': 0, 'items', [1,2,3]}, {'page_layout': 5, 'theme': 1, 'items', [4,5,6,7]}]

How can I isolate items to build chunk arrays like in the case above without objects...

I was tried: output = conditionalChunk(input.flat().items, 3, { 0: 2, 1: 2 }); but that is not the solution and I got error" Uncaught TypeError: array is not iterable

Then what do you want to do here? The code you tried hinted at trying to extract the items as a flat array. If you don't want to do that, there is probably no reason to flatten anything. You'd need to explain what the goal is. What do you want to go over and how? What is the expected output? — VLAZ
– VLAZ, Commented Jul 4, 2021 at 10:52
expected output need to be like [{'page_layout': 1, 'items': [1,2]}, {'page_layout': 2, 'items': [3,4]}, [{'page_layout': some_variable, 'items': [5,6,7]}]] so I need to move item array elements from an object to other — Aleks Per
– Aleks Per, Commented Jul 4, 2021 at 10:58

ravvis · Accepted Answer · 2021-07-04 10:19:59Z

1

You can extract all the items out first and then flatten them, like this -

const flattenedInputs = input.map(({ items }) => items).flat()
output = conditionalChunk(flattenedInputs, 3, { 0: 2, 1: 2 });

answered Jul 4, 2021 at 10:19

ravvis

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5 Comments

Aleks Per Over a year ago

that's ok, I got [[1,2],[3,4],[5,6]] but I lose the object data because I need to get array-like: [{'page_layout': 1, 'items': [1,2]}, {'page_layout': 2, 'items': [3,4]}, [{'page_layout': some_variable, 'items': [5,6,7]}];];

ravvis Over a year ago

Okay, and how will you decide the page_layout of each chunk(page)? if you have a predefined way to do that, then you can add these information while pushing to output output.push({ items: copy.splice(0, rules[i++] ?? size) , page_layout: getPageLayout })

Aleks Per Over a year ago

page_layout stay the same as it is... for new chunk its etc. 8

ravvis Over a year ago

Okay, and what if a chunk is made up of items from two different objects with different pag_layouts?

Aleks Per Over a year ago

page_layout stay the same but if new chunk need to be created then page_layout will be: 8

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