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If / Else Statements

Control your program's flow with if/else statements. Learn comparison operators, truthy/falsy values, and how to make decisions in JavaScript.

javascriptbasic

An if statement runs a block of code only when a condition is true.

Basic If

const age = 20;


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

If / Else

if (age >= 18) {
  console.log("adult");
} else {
  console.log("minor");
}

One branch or the other always runs.

Else If

const score = 75;


if (score >= 90) {
  console.log("A");
} else if (score >= 80) {
  console.log("B");
} else if (score >= 70) {
  console.log("C");
} else {
  console.log("F");
}

JavaScript checks each condition in order and stops at the first true.

Comparison Operators

Operator Meaning
=== Strictly equal
!== Strictly not equal
> Greater than
< Less than
>= Greater than or equal
<= Less than or equal

Always use === over ==. Triple equals checks value AND type, which is almost always what you want.

Truthy and Falsy

Any value can be used as a condition. Falsy values (0, '', null, undefined, NaN, false) evaluate to false. Everything else is truthy:

const name = "";


if (name) {
  console.log("has name"); // skipped — empty string is falsy
} else {
  console.log("no name"); // runs
}

Logical Operators

Combine conditions with && (AND) and || (OR):

if (age >= 18 && hasTicket) {
  console.log("enter");
}


if (isAdmin || isModerator) {
  console.log("access granted");
}