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

You could take a Map for grouping same id and get the values from the map as result set.

The result set has the same order of the wanted keys.

function groupBy(array, key) {
    return Array.from(array
        .reduce((m, o) => m.set(o[key], [...(m.get(o[key]) || []), o]), new Map)
        .values()
    );
}

var data = [{ 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' }],
    grouped = groupBy(data, 'id');

console.log(grouped);

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