为什么这个和/或场景评估为假？

Question

Why does this return false ?

var flavor = "chocolate";
console.log(flavor == ("vanilla" || "chocolate")); 

and if I type instead:

var flavor = "chocolate";
console.log(flavor == ("vanilla" && "chocolate"));

it returns true . This doesn't make sense to me because logically, flavor cannot equal both chocolate and vanilla. Can someone help me understand how I should be thinking through this?

Answer 1

(flavor == ("vanilla" || "chocolate")) returns false because ("vanilla" || "chocolate") returns as "vanilla" , so you're actually comparing "chocolate" == "vanilla" , which returns false .

(flavor == ("vanilla" && "chocolate")) returns true because ("vanilla" && "chocolate") returns as "chocolate" , so "chocolate" == "chocolate" obviously returns true .

I think what you actually want is (flavor == "vanilla" || flavor == "chocolate") and (flavor == "vanilla" && flavor == "chocolate") . Give that a try :)