Javascript [Electronic resources] : The Definitive Guide (4th Edition) نسخه متنی

3.7 null

The JavaScript keyword
null is a special value that indicates no value.
null is usually considered to be a special value
of object type -- a value that represents no object.
null is a unique value, distinct from all other
values. When a variable holds the value
null, you know that it does not contain a valid
object, array, number, string, or boolean value.[5]

C and C++ programmers should
note that null in JavaScript is not the same as
0, as it is in those languages. In certain
circumstances null is converted to
0, but the two are not equivalent.