Add an ordinal suffix to a number

Append st, nd, rd or th to a positive integer.

JavaScript Version 1.0.0 · MIT · .md

function addOrdinal(n) { return `${n}${['st', 'nd', 'rd'][((((n + 90) % 100) - 10) % 10) - 1] || 'th'}`; }

Input & expected output

22

"22nd"

The edge case

13

"13th"

Know the limits

• 11, 12 and 13 take th, as the edge case shows. English only; use Intl.PluralRules({ type: "ordinal" }) for other languages.

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.
• Calculate Fibonacci numbers — Return the nth Fibonacci number with memoized recursion.