Switch

If you're already tired of the if-else statement, I have some great news for you! In TypeScript, there's another construct for checking multiple conditions - the switch-case statement. This construct was created to execute code based on the value that's being passed. Let's take a look at the definition:

The syntax for the switch-case statement looks like this:

Key points about the switch statement in TypeScript:

break: Typically, each case includes a break statement to exit the switch after executing the code in the corresponding case. This prevents the execution of code from other case branches. The break statement is optional, and without it, execution will continue to the next case;
default: default is an optional block that executes if none of the case values match the expression. It acts as an alternative for all case branches.

The course author is running out of imagination, so let's look at the example with the days of the week again. However, this time we will slightly change the conditions, and now we will determine the name of the day of the week by its number in the week:


              123456789101112131415161718
            
let day: number = 3;
let dayName: string;

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

console.log(`Today is ${dayName}`);

Note

Note that if none of the values match, we execute the default block.

We use the variable day as an expression, and depending on its value, we determine the name of the day of the week. This way, we can create multiple conditions and execute specific code based on them.

1. What is the purpose of the `switch` statement in TypeScript?

2. What is the role of the `default` case in a `switch` statement?

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 6