Reduce
Reduce
π¨βπΌ Excellent! You've tackled
reduce, the most versatile array method.π¦
reduce can do almost anything, but that doesn't mean you should use it for
everything. Often map + filter is clearer:// Using reduce (clever but harder to read)
const total = products.reduce((sum, p) => (p.inStock ? sum + p.price : sum), 0)
// Using filter + reduce (clearer intent)
const total = products
.filter((p) => p.inStock)
.reduce((sum, p) => sum + p.price, 0)
Use
reduce when you need:- Sums/averages
- Finding min/max
- Grouping/counting
- Building objects from arrays
Immutable vs mutable accumulators: We used the spread pattern
({ ...acc, [key]: value }) which creates a new object each iteration. This
is easier to reason about and is the functional approach. For very large
arrays (thousands of items), mutating the accumulator directly is faster.
Pragmatism winsβchoose based on your actual data size and readability needs.
