distribute.js

const itemList = [
    { type: 'TRIANGLE', color: 'RED' },
    { type: 'TRIANGLE', color: 'BLUE' },
    { type: 'SQUARE', color: 'GREEN' },
];

const bucketList = [
    {
        name: 'TRIANGLES',
        condition: (i) => i.type === 'TRIANGLE'
    }
]

const distribute = (items, buckets = []) => {    
    return items.reduce((sorted, currentItem) => {
        if (!sorted['UNSORTED']) {
            sorted['UNSORTED'] = [];
        }

        for (let i = 0; i < buckets.length; i++) {
            const bucketName = buckets[i].name;
            const bucketExists = Array.isArray(sorted[bucketName]);
            const passesCondition = buckets[i].condition(currentItem);

            if (!bucketExists && bucketName && passesCondition) {
                sorted[bucketName] = [currentItem];
                break;
            } else if (bucketExists && passesCondition) {
                sorted[bucketName].push(currentItem);
                break;
            } else {
                sorted['UNSORTED'].push(currentItem);
                break;
            }
        }

        return sorted;
    }, {});
}

const distributed = distribute(itemList, bucketList);