Sum of Numbers

Console

BeginnerArrays

Task

Implement `sum(nums)` that returns the total of all numbers in the array. An empty array sums to `0`. This is the textbook `.reduce()` exercise — compare the loop version against it once you're done.

Hints

0 / 2

reduce needs an initial value: nums.reduce((acc, n) => acc + n, 0).
Without the initial 0, reduce on an empty array throws.

Verification tests

sum([1,2,3,4])→ 10
sum([-1,1])→ 0
sum([100])→ 100
sum([])→ 0

⚠️ Reveal official solutions

Try solving it yourself first — struggling is where the learning happens.

Recommended — idiomatic reduce; keep the 0 initial value so empty arrays work.

function sum(nums) {
  return nums.reduce((total, n) => total + n, 0);
}

Use when the team finds reduce hard to read, or when you need an early exit.

function sum(nums) {
  let total = 0;
  for (const n of nums) {
    total += n;
  }
  return total;
}

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