however, these format specifiers do not seem to exist for the standard, user-space (s)printf. Node.js Recipes The solution to all Node problems. Converting a hex string into a BYTE array JS.Im not sure this is what youre after, but you can convert the string to an array of hex values like this: var str "00010203040506070809", a  > hex-string1.0.0 bench hex-string.Notes. Tested against nodes Buffer for compatibility. Decode returns Uint8Array instead of Buffer.