If Statements in JavaScript

The if statement lets your code make decisions — running different code based on whether a condition is true or false.

Basic If Statement

let age = 20;

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

The code inside the curly braces only runs if the condition in parentheses is true.

If...Else

let temperature = 35;

if (temperature > 30) {
    console.log("It's hot outside!");
} else {
    console.log("It's not too hot.");
}

Multiple Conditions

let score = 85;

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

Nested If Statements

let isLoggedIn = true;
let isAdmin = false;

if (isLoggedIn) {
    if (isAdmin) {
        console.log("Welcome, Admin!");
    } else {
        console.log("Welcome, User!");
    }
} else {
    console.log("Please log in.");
}

Ternary Operator (Short If)

let age = 20;
let status = age >= 18 ? "adult" : "minor";
console.log(status);  // "adult"