Truncate a number at decimal

Drop the fractional part toward zero.

JavaScript Version 1.0.0 · MIT · .md

function truncate(n) { return Math.trunc(n); }

Input & expected output

12.75

12

The edge case

-12.75

-12

Know the limits

• The original ~~n only works within 32 bits: ~~3000000000 is -1294967296. Math.trunc works for every number.

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.