November 2001
Intermediate to advanced
936 pages
68h 43m
English
NaN — the not-a-number property
JavaScript 1.3; JScript 3.0; ECMAScript v1
NaN
NaN is global property that refers to the special
numeric not-a-number value. The NaN property is
not enumerated by for/in loops and cannot be
deleted with the delete operator. Note that
NaN is not a constant and can be set to any other
value, something that you should take care not to do.
To determine if a value is not a number, use isNaN( ), since NaN always compares non-equal
to any other value, including itself!