group array of objects by id

Question

I am trying to loop through a array ob objects and group the items of the array into new arrays that have matching id:

API example:

    api_array [
          


        

Answer 1

Similar to your reduce example, this iterates over the data and creates a object using the object ids as keys and grouping them together. It then grabs the values from that object.

const api_array = [{id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'}];

const out = Object.values(api_array.reduce((acc, c) => {
  const { id } = c;

  // If the object doesn't have a key that matches the id
  // create an array as its value and then concat the current object
  // to it, otherwise, if the key exists just concat the current object
  // to the existing array
  acc[id] = (acc[id] || []).concat(c);
  return acc;
}, {}));

console.log(out)