TrejitoChallange.js

const data = [
    {    
        idArtisan: 1,
        idProduct: 3,
        name: 'Aguila de madera',
        price: 800.00,
        quantity: 3,
        weight: 0.25
    },
    {
        idArtisan: 3,
        idProduct: 16,
        name: 'Portavasos - Cup holders',
        price: 199.00,
        quantity: 3,    
        weight: 0.50
    },
    {
        idArtisan: 1,
        idProduct: 15,
        name: 'Corona de Barro - Clay Crown',
        price: 699.00,
        quantity: 1,
        weight:0.15
    },
    {
        idArtisan: 3,
        idProduct: 20,
        name: 'Craneo de Barro',
        price: 1250.00,
        quantity: 1,
        weight: 1.00
    }
]

data.map(x => ({
    idArtisan: x.idArtisan,
    price: x.price * x.quantity,
    weight: x.weight * x.quantity,
})).reduce((acum, curr, i) => {
    var iia = acum.findIndex(x => x.idArtisan === curr.idArtisan);
    if (iia > -1) {
        acum[iia].price += curr.price;
        acum[iia].weight += curr.weight;
    } else {
        acum.push(curr)
    }
    return acum;
}, [])