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JavaScriptIntermediate#numbers
JavaScriptBeginner#numbers
What is NaN and how do you check for it?
NaN is the numeric result of an invalid computation and is the only value not equal to itself. Use Number.isNaN, which does not coerce, rather than the legacy global isNaN.
Example
0/0; // NaN
NaN === NaN; // false
Number.isNaN('a'); // false
isNaN('a'); // true (coerces)