For example, you declare a variable
foo and assign
NaN to the variable, i.e
let foo = NaN;. Then you might think checking can be done this way:
let foo = NaN; foo === NaN; // false Number.NaN === foo ; // false
However, the expectation is otherwise.
isNaN(foo); // true Number.isNaN(foo); // true
To avoid confusion, please use
isNaN() to check whether a variable is Not-a-Number or not.
Author: Wu Chia Chong
My main areas of interest are software architectures and software design methods, patterns, and new trends in software development.