hasOwnProperty object prototype function


hexadecimal base 16

The hexadecimal digits are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, and f. The hexadecimal digits a b c d e and f can also be represented in uppercase. The lowercase form is slightly preferred because it is easier to confuse B with 8 than b with 6.

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 toString Number prototype function.

higher order function




host object

A host object is an object that is not a ECMAScript object, but that can be interacted with by ECMAScript programs. It might be provided by the host operating system. The ECMAScript standard does not require that there be any host objects, but implementations are allowed to provide them. Host objects, because they are not JavaScript objects, might act funny. You know, funny. Also see native object.