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Array reduce explained

reduce is the most powerful and most misunderstood array method. AI uses it for aggregations.

arraysreduceaggregationaccumulation
javascript
const orders = [
  { product: 'Book', price: 12, qty: 2 },
  { product: 'Pen', price: 3, qty: 5 },
  { product: 'Notebook', price: 8, qty: 1 }
]

const total = orders.reduce((acc, order) => {
  return acc + (order.price * order.qty)
}, 0)

const byProduct = orders.reduce((acc, order) => {
  acc[order.product] = order.price * order.qty
  return acc
}, {})

Question

What are the values of total and byProduct?

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