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

Igor Kałużny
Igor Kałużny
4,337 Points

Or || statement

isNaN(lower || upper) vs isNaN(lower) || isNan(upper)

can I use the first one?

1 Answer

Christopher Debove
Christopher Debove
Courses Plus Student 18,373 Points

Its not the same =)

Here some examples:

lower = 3
upper = 4
isNaN(lower || upper) // return false
isNaN(lower) || isNaN(upper) // return false

lower = null
upper = 4
isNaN(lower || upper) // return false because what's evaluated is : isNaN(upper)
isNaN(lower) || isNaN(upper) // return true because : isNaN(lower) = true;

In the first case the value of argument you're passing to isNaN is the first non-falsy variable (falsy variable : "", 0, null, undefined)