Check if a string is a hexadecimal number

Test for one or more hexadecimal digits.

JavaScript Version 1.0.0 · MIT · .md

function isHexadecimal(text) { return /^[0-9a-f]+$/i.test(text); }

Input & expected output

"ff00"

true

The edge case

"0xff"

false

Know the limits

• A 0x prefix fails, as the edge case shows; strip it 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.

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.