Switch Statement

Part of the Fundamentals section of Coddy's JavaScript journey — lesson 27 of 77.

The switch statement is another way to control the flow of your program based on different conditions. It's similar to using if-else if-else, but it can be more concise and readable in certain situations.

Here's how the switch statement works:

switch (expression) {
    case value1:
        // Code to execute if expression matches value1
        break;
    case value2:
        // Code to execute if expression matches value2
        break;
    // ... more cases ...
    default:
        // Code to execute if no case matches
}

The expression is evaluated once.
The value of the expression is compared with the values of each case.
If there is a match, the associated block of code is executed.

The break statement is used to exit the switch statement. Without it, execution would continue to the next case.

The default case is optional. It's executed if no other case matches.

Here's an example:

let day = 3;
let dayName;

switch (day) {
    case 1:
        dayName = "Sunday";
        break;
    case 2:
        dayName = "Monday";
        break;
    case 3:
        dayName = "Tuesday";
        break;
    // ... cases for other days ...
    default:
        dayName = "Invalid day";
}

console.log(dayName); // Output: Tuesday

In this example, the switch statement checks the value of day. Since day is 3, the case for 3 is executed, setting dayName to "Tuesday".

Challenge

Beginner

You will receive a command from the user.
Use a switch statement to set the value of the variable message based on the command.

Set message to:

"System starting" → if the command is "start"
"System stopping" → if the command is "stop"
"System paused" → if the command is "pause"
"System resuming" → if the command is "resume"

If the command doesn't match any known option, set:

"Unknown command"

At the end, the program will print the value of message.
Your job is to correctly set the value of <strong>message</strong> using a switch statement.

Cheat sheet

The switch statement controls program flow based on different conditions, similar to if-else if-else but more concise for certain situations.

Basic syntax:

switch (expression) {
    case value1:
        // Code to execute if expression matches value1
        break;
    case value2:
        // Code to execute if expression matches value2
        break;
    default:
        // Code to execute if no case matches
}

The expression is evaluated once and compared with each case value
The break statement exits the switch; without it, execution continues to the next case
The default case is optional and executes if no other case matches

Example:

let day = 3;
let dayName;

switch (day) {
    case 1:
        dayName = "Sunday";
        break;
    case 2:
        dayName = "Monday";
        break;
    case 3:
        dayName = "Tuesday";
        break;
    default:
        dayName = "Invalid day";
}

console.log(dayName); // Output: Tuesday

Try it yourself

// Get the command from the user
let command = inp;

// Create a variable to store the message
let message;

switch (command) {
    // Write your code here
}

// Print the message
console.log(message);