JavaScript Switch Statements

What is a Switch Statement?

A switch statement is a way to check a value against multiple options. Instead of writing many if/else statements, you use switch to make your code cleaner and easier to read

Think of it like:

A TV remote with numbered buttons (1 = CNN, 2 = ESPN, 3 = HBO)
A vending machine (A1 = Chips, B2 = Soda, C3 = Candy)
A restaurant menu (selecting from options)

Switch Statement Syntax

javascript

switch (value) {
  case option1:
    // Code if value === option1
    break;
  case option2:
    // Code if value === option2
    break;
  case option3:
    // Code if value === option3
    break;
  default:
    // Code if no match
}

Important parts:

switch – the keyword that starts the switch statement
case – each possible value to check
break – stops checking more cases
default – runs if nothing matches (optional)

Example 1: Day of the Week

javascript

let day = 3;

switch (day) {
  case 1:
    console.log("Monday");
    break;
  case 2:
    console.log("Tuesday");
    break;
  case 3:
    console.log("Wednesday");
    break;
  case 4:
    console.log("Thursday");
    break;
  case 5:
    console.log("Friday");
    break;
  case 6:
    console.log("Saturday");
    break;
  case 7:
    console.log("Sunday");
    break;
  default:
    console.log("Invalid day");
}

Example 2: Traffic Light

javascript

let light = "red";

switch (light) {
  case "red":
    console.log("Stop!");
    break;
  case "yellow":
    console.log("Slow down");
    break;
  case "green":
    console.log("Go");
    break;
  default:
    console.log("Light is broken");
}

// Output: Stop!

Multiple Cases and Fall-Through

Sometimes multiple cases should do the same thing. You can group them together!

Example 1: Weekend vs Weekday

javascript

let day = "Saturday";

switch (day) {
  case "Monday":
  case "Tuesday":
  case "Wednesday":
  case "Thursday":
  case "Friday":
    console.log("It's a weekday - time to work!");
    break;
  case "Saturday":
  case "Sunday":
    console.log("It's the weekend - relax!");
    break;
  default:
    console.log("Invalid day");
}

// Output: It's the weekend - relax!

How it works:

Multiple cases share the same code
Only need one break at the end
Like saying “if any of these, do this”

Understanding Fall-Through Behavior

Fall-through happens when you forget the break statement. The code keeps running into the next case!

Example: Fall-Through (Without Break)

javascript

let number = 2;

switch (number) {
  case 1:
    console.log("One");
    // No break! Falls through to case 2
  case 2:
    console.log("Two");
    // No break! Falls through to case 3
  case 3:
    console.log("Three");
    break;
  default:
    console.log("Other");
}

// Output:
// Two
// Three

What happened:

Matched case 2
Printed Two
No break, so continued to case 3
Printed Three
Hit break and stopped execution

When Fall-Through is Useful

Sometimes you WANT fall-through behavior:

Example :

javascript

Sometimes you WANT fall-through behavior:
let level = 3;
let permissions = [];

switch (level) {
  case 3:
    permissions.push("delete");
    // Fall through - level 3 gets all permissions
  case 2:
    permissions.push("edit");
    // Fall through - level 2 gets edit and view
  case 1:
    permissions.push("view");
    break;
  default:
    console.log("No permissions");
}

console.log("Permissions: " + permissions);
// Output: Permissions: delete,edit,view

Fall-Through Warning Example

javascript

// ❌ WRONG - Forgot break statements
let choice = 1;

switch (choice) {
  case 1:
    console.log("Starting game...");
    // Missing break!
  case 2:
    console.log("Loading game...");
    // Missing break!
  case 3:
    console.log("Exiting game...");
    break;
}

// Output (WRONG):
// Starting game...
// Loading game...
// Exiting game...

✅ CORRECT

javascript

// ✅ CORRECT - With break statements
switch (choice) {
  case 1:
    console.log("Starting game...");
    break;  // Stops here
  case 2:
    console.log("Loading game...");
    break;
  case 3:
    console.log("Exiting game...");
    break;
}

// Output (CORRECT):
// Starting game...
Practice Problems for Beginners

Practice 1: Month Number to Name

javascript

Convert month numbers (1-12) to month names.
function getMonthName(monthNumber) {
  switch (monthNumber) {
    case 1:
      return "January";
    case 2:
      return "February";
    case 3:
      return "March";
    case 4:
      return "April";
    case 5:
      return "May";
    case 6:
      return "June";
    case 7:
      return "July";
    case 8:
      return "August";
    case 9:
      return "September";
    case 10:
      return "October";
    case 11:
      return "November";
    case 12:
      return "December";
    default:
      return "Invalid month number";
  }
}

console.log(getMonthName(3));  // March
console.log(getMonthName(12)); // December
console.log(getMonthName(13)); // Invalid month numbe