Reduce

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Reduce

👨‍💼 The reduce method accumulates an array into a single value. It's the most powerful (and sometimes confusing) array method—and a cornerstone of functional programming.

const numbers = [1, 2, 3, 4]
const sum = numbers.reduce((acc, n) => acc + n, 0)
// 10

Parameters:

accumulator (acc) - The running total
current (n) - The current element
initial value (0) - Starting point

🐨 Open

index.ts

and use the provided products fixture:

Create total with reduce — sum of all prices, starting from 0 (expected 1579.95)
Create mostExpensive with reduce — the product object with the highest price (expected name 'Laptop', price 999.99)
Create countByCategory with reduce — an object of category counts (expected { Electronics: 3, Kitchen: 2 })
Export total, mostExpensive, and countByCategory

💰 reduce combines all items into one accumulated result.

💰 When counting with an object accumulator, you can either update a single object or return a new object each step — choose the approach you find clearer.

📜 MDN - Array.prototype.reduce()

05. Array Methods/03. Reduce (💪 problem)

Reduce