Get the intersection range between two ranges

Return the overlap of two closed ranges, or an empty array.

JavaScript Version 1.0.0 · MIT · .md

function intersectRanges({ a, b }) { return a[0] > b[1] || a[1] < b[0] ? [] : [Math.max(a[0], b[0]), Math.min(a[1], b[1])]; }

Input & expected output

{
  "a": [
    1,
    10
  ],
  "b": [
    5,
    15
  ]
}

[
  5,
  10
]

The edge case

{
  "a": [
    1,
    2
  ],
  "b": [
    3,
    4
  ]
}

[]

Know the limits

• Ranges are [start, end] with start ≤ end; touching ranges overlap in one point.

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

• Clamp a number to a range — Keep a number inside an inclusive minimum and maximum.
• Round to a number of digits — Apply decimal scaling and JavaScript rounding for display-oriented values.
• Add an ordinal suffix to a number — Append st, nd, rd or th to a positive integer.