Destructuring objects from an array using map?

Question

I have wrote this simple code that destructures an array of objects to build new arrays from each key. I am learning ES6 and would like to refactor it into one line of code

Answer 1

So you should start with reduce first and return an object. Then you can use destructuring on that. Here's an example:

const candles = [{
  open: 1,
  high: 2,
  low: 0.5,
  close: 1.5,
  volume: 200
}, {
  open: 2,
  high: 3,
  low: 0.6,
  close: 1.4,
  volume: 300
}];

const reduction = candles.reduce((acc, candle) => {
  for (let key in candle) {
    if (!(key in acc)) {
      acc[key] = [];
    }

    acc[key].push(candle[key]);
  }

  return acc;
}, {});

console.log(reduction);
// { open: [ 1, 2 ],
//   high: [ 2, 3 ],
//   low: [ 0.5, 0.6 ],
//   close: [ 1.5, 1.4 ],
//   volume: [ 200, 300 ] }

const {open, high, low, close, volume} = reduction;

console.log(open, high, low, close, volume);
// [ 1, 2 ] [ 2, 3 ] [ 0.5, 0.6 ] [ 1.5, 1.4 ] [ 200, 300 ]