CODEWITHSUNDEEP
javascript
Sara Ree
Sara Ree

Reputation: 3543

order and organize array of objects

I have this array of objects and I want to organize the objects based on their units like this:

const array = [
  { unit: 5, id: 'five'},
  { unit: 200, id: 'some22'},
  { unit: 100, id: 'recall'},
  { unit: 5, id: 'some'},
];

// Result :

[

  [ { unit: 5, id: 'five'}, { unit: 5, id: 'some'}, ],
  [ { unit: 6, id: 'some22'} ],
  [ { unit: 55, id: 'recall'} ],

]

Note: we can simply use filter method to get the array but in my case we don't know the units and we just want to order and organize them

Upvotes: 1

Views: 72

Answers (2)

Sash Sinha
Sash Sinha

Reputation: 22360

You could use a Map:

const array = [
    { unit: 5, id: 'five'},
    { unit: 200, id: 'some22'},
    { unit: 100, id: 'recall'},
    { unit: 5, id: 'some'},
];

const unitGroups = new Map();
for (const obj of array) {
    if (!unitGroups.has(obj.unit)) {
        unitGroups.set(obj.unit, []);
    }
    unitGroups.get(obj.unit).push(obj);
}

const result = Array.from(unitGroups.values());
console.log(result);

Upvotes: 1

winner_joiner
winner_joiner

Reputation: 14730

A different approach using the build in array method reduce, just to create a one-liner. Details to the under appreciated reduce function Array.prototype.reduce 

// Initial Data
const array = [
  { unit: 5, id: 'five'},
  { unit: 200, id: 'some22'},
  { unit: 100, id: 'recall'},
  { unit: 5, id: 'some'},
];

let result = array.reduce (function(last, next){ 
  // find index of a List with matching unit
  let index = last.findIndex((itemList) => itemList.some( item => item.unit == next.unit)); 
  if(index == -1){ // if no match was found
    index = last.push([]) - 1; // add an empty Array and set the index
  }
  last[index].push(next);  // add the Entry to the selected List
  return last;
}, [])

console.info(result);

btw.: I'm asuming the posted result data is incorrect, since the "units" for some22 and recall don't match with the initial data. If this assumption is wrong please clarify

Extra: just for kicks and giggles the whole thing as a real one-liner:
( Don't try this at home ;-) )

const array = [
  { unit: 5, id: 'five'},
  { unit: 200, id: 'some22'},
  { unit: 100, id: 'recall'},
  { unit: 5, id: 'some'},
];

console.info( array.reduce((p, c) => ((p.find( l => l.some(i => i.unit == c.unit)) || p[p.push([]) - 1]).push(c), p), []));

Upvotes: 1

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