Best way to get two nibbles out of a byte in javascript?

Question

I\'m parsing a binary file in javascript that is storing two pieces of information per byte, one per nibble. The values are, of course, 0-16 and 0-16.

In all other parts

Answer 1

var num = str.charCodeAt(0) & 0xFF;
var nibble1 = num & 0xF;
var nibble2 = num >> 4;