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JavaScript JavaScript Basics (Retired) Creating Reusable Code with Functions Random Number Challenge, Part II Solution

Posted by Henry Stiltner
Henry Stiltner
4,178 Points

Couldn't we just use typeof instead of isNaN?

Wouldn't it be a lot simpler if we just used typeof instead of isNaN? typeof seems more straightforward to me when testing for value types. isNaN and Number.isNaN seem overly complicated.

1 Answer

Seth Kroger
Seth Kroger
56,413 Points
Seth Kroger
Seth Kroger
56,413 Points

Let's try that in the browser console:

let num = NaN
 // undefined
num
  // NaN
typeof num
  // "number"   ...What?

That's because NaN is a special value. It's not so much "this value is something other than a number" as "this numeric value cannot be represented by a real number."