CodeToLive

Control Structures in JavaScript

Control structures in JavaScript allow you to control the flow of your program. They include conditional statements (if-else, switch), loops (for, while, do-while), and error handling (try-catch).

If-Else Statements

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

let age = 20;
if (age >= 18) {
    console.log("You are an adult.");
} else {
    console.log("You are a minor.");
}
      

Ternary Operator

The ternary operator is a shorthand for the if-else statement.

let age = 20;
let message = age >= 18 ? "You are an adult." : "You are a minor.";
console.log(message);  // Output: You are an adult.
      

Switch Statement

The switch statement is used to execute one of many code blocks based on the value of an expression.

let day = 3;
switch (day) {
    case 1:
        console.log("Monday");
        break;
    case 2:
        console.log("Tuesday");
        break;
    default:
        console.log("Invalid day");
}
      

Loops

Loops are used to execute a block of code repeatedly. JavaScript supports for, while, do-while, for...of, and for...in loops.

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

// While Loop
let count = 0;
while (count < 5) {
    console.log(count);
    count++;
}

// Do-While Loop
let x = 0;
do {
    console.log(x);
    x++;
} while (x < 5);

// For...of Loop (for arrays)
let fruits = ["Apple", "Banana", "Cherry"];
for (let fruit of fruits) {
    console.log(fruit);
}

// For...in Loop (for objects)
let person = { name: "Alice", age: 25 };
for (let key in person) {
    console.log(`${key}: ${person[key]}`);
}
      

Error Handling: Try-Catch

The try-catch statement is used to handle errors gracefully.

try {
    let result = 10 / 0;
    if (!isFinite(result)) {
        throw new Error("Division by zero is not allowed.");
    }
} catch (error) {
    console.log(error.message);  // Output: Division by zero is not allowed.
} finally {
    console.log("Execution completed.");
}