JavaScript Conditional Statements

Conditional statements in JavaScript are used to perform different actions based on different conditions. Here are the main types of conditional statements:

1. if Statement

Syntax

if(condition){
    // code to be executed if condition is true
}

Example

let age = 20;

if (age >= 18) {
    console.log(“You are an adult.”); // Output: You are an adult.
}




2. if...else Statement

Syntax

if (condition) {
    // code to be executed if condition is true
} else {
    // code to be executed if condition is false
}

Example

let age = 16;

if (age >= 18) {
    console.log(“You are an adult.”);
} else {
    console.log(“You are a minor.”); // Output: You are a minor.
}

3. if...else if...else Statement

Syntax

if (condition1) {
    // code to be executed if condition1 is true
} else if (condition2) {
    // code to be executed if condition2 is true
} else {
    // code to be executed if all conditions are false
}

Example

let score = 85;

if (score >= 90) {
    console.log(“Grade: A”);
} else if (score >= 80) {
    console.log(“Grade: B”); // Output: Grade: B
} else if (score >= 70) {
    console.log(“Grade: C”);
} else if (score >= 60) {
    console.log(“Grade: D”);
} else {
    console.log(“Grade: F”);
}

4. switch Statement

Syntax

switch (expression) {
    case value1:
        // code to be executed if expression === value1
        break;
    case value2:
        // code to be executed if expression === value2
        break;
    // more cases…
    default:
        // code to be executed if no cases match
}

Example

let day = 3;
let dayName; 

switch (day) {
    case 1: 
        dayName = “Monday”;
        break;
    case 2:
        dayName = “Tuesday”;
        break;
    case 3:
        dayName = “Wednesday”; // Output: Wednesday
        break;
    case 4:
        dayName = “Thursday”;
        break;
    case 5:
        dayName = “Friday”;
        break;
    case 6:
        dayName = “Saturday”;
        break;
    case 7:
        dayName = “Sunday”;
        break;
    default:
        dayName = “Invalid day”;
}

console.log(dayName);

Syntax

condition ? expressionIfTrue : expressionIfFalse;

Example

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