JavaScript Operators

let a = 10, b = 3;

console.log(a + b);   // 13 — addition
console.log(a - b);   // 7  — subtraction
console.log(a * b);   // 30 — multiplication
console.log(a / b);   // 3.33 — division
console.log(a % b);   // 1  — remainder (modulo)
console.log(a ** b);  // 1000 — exponentiation (10³)

// Increment / Decrement
let x = 5;
x++;  // x is now 6 (post-increment)
x--;  // x is now 5 (post-decrement)
++x;  // increment THEN use value

let n = 10;
n += 5;   // n = n + 5  → 15
n -= 3;   // n = n - 3  → 12
n *= 2;   // n = n * 2  → 24
n /= 4;   // n = n / 4  → 6
n **= 2;  // n = n ** 2 → 36
n %= 5;   // n = n % 5  → 1

// == (loose) vs === (strict) — always use ===
5 == "5"   // true  — type coercion (dangerous!)
5 === "5"  // false — different types, no coercion
5 !== "5"  // true  — use !== instead of !=

10 > 5    // true
10 < 5    // false
10 >= 10  // true
10 <= 9   // false

// && (AND) — both must be true
true && true   // true
true && false  // false

// || (OR) — at least one must be true
false || true  // true
false || false // false

// ! (NOT) — inverts
!true   // false
!false  // true

// Short-circuit evaluation
const name = "" || "Guest";   // "Guest" (falsy || fallback)
const user = null;
const age  = user && user.age; // null (stops at null)

// condition ? value-if-true : value-if-false
const age = 20;
const status = age >= 18 ? "adult" : "minor";
console.log(status); // "adult"

// In JSX / template strings
const msg = `You are ${age >= 18 ? "allowed" : "not allowed"}`;

// ?? returns right side only if left is null or undefined
// Different from || which triggers on ANY falsy value (0, "", false)
const score = 0;
score || 100   // 100  (wrong! 0 is falsy)
score ?? 100   // 0    (correct! 0 is not null/undefined)

const config = null;
config ?? "default"  // "default"