Comparing NaN values for equality in Javascript

Question

I need to compare two numeric values for equality in Javascript. The values may be NaN as well. I\'ve come up with this code:

if (val1 == val2 |         


        

Answer 1

For Numeric cases the solution is fine but to extend it to work for other data-types as well my suggestion would be as follows:

if(val1 === val2 || (val1 !== val1 && val2 !== val2))

Reason being global isNaN is erroneous. It will give you wrong results in scenarios like

isNaN(undefined); // true
isNaN({});        // true
isNaN("lorem ipsum"); // true 

I have posted a comprehensive answer here which covers the NaN comparison for equality as well.

How to test if a JavaScript variable is NaN