Find the index of the minimum item of an array

Return the index of the first smallest number.

JavaScript Version 1.0.0 · MIT · .md

find-the-index-of-the-minimum-item-of-an-array.js
function indexOfMin(values) { return values.reduce((best, value, i) => (value < values[best] ? i : best), 0); }

Input & expected output

Input

[
  6,
  4,
  8,
  2,
  2
]

Expected output

3

The edge case

Input

[]

Expected output

0

Know the limits

  • The first minimum wins on ties. An empty array returns 0 — check the length first.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Source & maintenance

Based on Find the index of the minimum item of an array from the original 1loc collection by Nguyen Huu Phuoc. Copyright (c) 2020 phuoc-ng. MIT licensed.

Curated implementation; explicit input contract, edge case and limits. Original MDX retained as inert source evidence.

Maintained by Oveyon. Source commit: 14b481cf60df. Read the license.

Local fixture scope · Node.js 22.23.2 · reviewed October 28, 2026. No external service is required.

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