hasOwnPropertyobject prototype function
The hexadecimal digits are
f. The hexadecimal digits
f can also be represented in uppercase. The lowercase form is slightly preferred because it is easier to confuse
Unlike the decimal system which uses base 10, the hexadecimal system uses base 16, where each hexadecimal digit represents exactly 4 bits. In olden times, programming was closer to the machine so a format that was trivially convertable to binary was highly desirable. Today, hexadecimal is mainly used to encode a code value in a Unicode escape sequence and to encode colors in CSS.
Also see number literal,
parseInt global function, and
Number prototype function.