JavaScript If-Else

In JavaScript, conditional statements allow you to execute different blocks of code based on certain conditions. The `if-else` statement is a fundamental control structure used to perform this conditional logic.

1. Basic If Statement

The simplest form of conditional statement is the `if` statement. It executes a block of code if a specified condition evaluates to `true`:

// Basic if statement
let age = 18;

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

            

2. If-Else Statement

The `if-else` statement provides an alternative block of code to execute when the condition is `false`:

// If-else statement
let age = 16;

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

            

3. If-Else If-Else Statement

The `if-else if-else` statement allows you to check multiple conditions in sequence:

// If-else if-else statement
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: D");
}

            

4. Nested If Statements

You can nest `if` statements inside other `if` statements to check multiple conditions:

// Nested if statements
let age = 25;
let hasLicense = true;

if (age >= 18) {
    if (hasLicense) {
        console.log("You can drive.");
    } else {
        console.log("You need a driving license.");
    }
} else {
    console.log("You are not old enough to drive.");
}