Conditionals

Conditionals control the flow of code by executing different blocks based on true/false evaluations.

1. if Statement

let age = 18;

if (age >= 18) {
  console.log("Adult");
}

2. if...else

if (age >= 18) {
  console.log("Adult");
} else {
  console.log("Minor");
}

3. if...else if...else

if (age < 13) {
  console.log("Child");
} else if (age < 18) {
  console.log("Teen");
} else {
  console.log("Adult");
}

4. Ternary Operator

Shorthand for if...else.

let msg = (age >= 18) ? "Adult" : "Minor";
console.log(msg);

5. Logical Operators

Operator	Name	Example	Result
&&	AND	a > 0 && b > 0	true if both
`		`	OR	`a > 0		b > 0`	true if either
!	NOT	!isLoggedIn	inverse

6. switch Statement

Efficient alternative to multiple if...else if.

let color = "blue";

switch (color) {
  case "red":
    console.log("Red selected");
    break;
  case "blue":
    console.log("Blue selected");
    break;
  default:
    console.log("No match");
}

• break is required to prevent fall-through
• default runs if no case matches

7. Falsy Values

These values are considered false in conditionals:

• false
• 0
• "" (empty string)
• null
• undefined
• NaN

if (!value) {
  console.log("Falsy value");
}