Check if a number is in a given range

Test an inclusive range whose ends may be given in any order, with an optional tolerance.

JavaScript Version 1.0.0 · MIT · .md

function inRange({ value, a, b, threshold = 0 }) { return Math.min(a, b) - threshold <= value && value <= Math.max(a, b) + threshold; }

Input & expected output

{
  "value": 5,
  "a": 10,
  "b": 1
}

true

The edge case

{
  "value": 10.5,
  "a": 1,
  "b": 10,
  "threshold": 0.5
}

true

Know the limits

• Both ends are included; threshold widens the range on both sides.

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.

Keep exploring

• Check whether all values are equal — Compare every item with the first using Object.is.
• Check whether an object is empty — Check for own enumerable string keys on a JSON object.
• Check whether an integer is even — Test parity for safe integers, including zero and negative values.