Booleans, comparisons, and ===

Booleans — true and false (lowercase in JavaScript!) — are the values every decision is made of.

Comparisons

Why === and not ==?

JavaScript also has a loose == that converts types before comparing — with famously surprising results:

5 == "5" is true?! Loose equality quietly converts the string, which sounds convenient and is actually a bug factory. The professional rule is simple: always use === and !==. Then a number never accidentally equals a string, and comparisons mean exactly what they say.

Logic: && || !

Combined with comparisons, this expresses real rules:

const canRideAlone = age >= 14 && hasHelmet;