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Control Flow Statements in TypeScript

Control flow statements are essential constructs that allow you to dictate the order in which statements are executed in your TypeScript programs. These statements enable you to make decisions, repeat actions, and handle exceptions, thereby creating more dynamic and responsive applications.

Below, we explore the various control flow statements available in TypeScript, complete with descriptions and examples to illustrate their use.

You will explore various control flow statements such as if...else, switch, for, for...of, for...in, while, do...while, break, continue, try...catch...finally, and throw, and learn how to use them effectively in your TypeScript programs.

1. if...else​

The if...else statement is used to execute a block of code based on a condition.

Example:

typescript
let age: number = 25;
if (age >= 18) {
    console.log("Adult");
} else {
    console.log("Minor");
}

2. switch​

The switch statement is used to perform different actions based on different conditions.

Example:

typescript
typescript

let fruit: string = "apple";
switch (fruit) {
    case "apple":
        console.log("Apple");
        break;
    case "banana":
        console.log("Banana");
        break;
    default:
        console.log("Unknown fruit");
}

3. for​

The for loop is used to execute a block of code a specified number of times.

Example:

typescript
for (let i = 0; i < 5; i++) {
    console.log(i);
}

4. for...of​

The for...of loop is used to iterate over the values of an iterable object (like an array).

Example:

typescript
let numbers: number[] = [1, 2, 3, 4];
for (let num of numbers) {
    console.log(num);
}

5. for...in​

The for...in loop is used to iterate over the keys of an object.

Example:

typescript
let person: { name: string, age: number } = { name: "Alice", age: 25 };
for (let key in person) {
    console.log(key + ": " + person[key]);
}

6. while​

The while loop is used to execute a block of code as long as a specified condition is true.

Example:

typescript
let count: number = 0;
while (count < 5) {
    console.log(count);
    count++;
}

7. do...while​

The do...while loop is similar to the while loop, but it will execute the block of code at least once before checking the condition.

Example:

typescript
let count: number = 0;
do {
    console.log(count);
    count++;
} while (count < 5);

8. break​

The break statement is used to exit a loop or a switch statement.

Example:

typescript
for (let i = 0; i < 5; i++) {
    if (i === 3) {
        break;
    }
    console.log(i);
}

9. continue​

The continue statement is used to skip the current iteration of a loop and continue with the next one.

Example:

typescript
for (let i = 0; i < 5; i++) {
    if (i === 3) {
        continue;
    }
    console.log(i);
}

10. try...catch...finally​

The try...catch...finally statement is used to handle exceptions and execute code regardless of whether an exception was thrown.

Example:

typescript
try {
    let result: number = 10 / 0;
    console.log(result);
} catch (error) {
    console.log("An error occurred: " + error.message);
} finally {
    console.log("This will always execute");
}

11. throw​

The throw statement is used to create a custom error.

Example:

typescript
function divide(a: number, b: number): number {
    if (b === 0) {
        throw new Error("Division by zero");
    }
    return a / b;
}

try {
    console.log(divide(10, 0));
} catch (error) {
    console.log("An error occurred: " + error.message);
}