Control Flow in JavaScript: if-else and switch

Control flow in JavaScript determines how code executes based on different conditions. The most common ways to control the flow of a program are if-else statements and switch statements.

1. if-else Statement

The if-else statement allows you to execute code based on a condition. If the condition is true, the block inside if runs. If it’s false, the else block runs (if provided).

Syntax:

if (condition) {
    // Code runs if condition is true
} else {
    // Code runs if condition is false
}

Example:

let age = 18;
if (age >= 18) {
    console.log("You are eligible to vote.");
} else {
    console.log("You are not eligible to vote.");
}

Output:

You are eligible to vote.

if-else-if Ladder

If you have multiple conditions, you can use else if.

let marks = 75;
if (marks >= 90) {
    console.log("Grade: A");
} else if (marks >= 75) {
    console.log("Grade: B");
} else {
    console.log("Grade: C");
}

Output:

Grade: B

2. switch Statement

The switch statement is used when there are multiple possible conditions for a single variable. Instead of using multiple if-else, a switch provides a cleaner approach.

Syntax:

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

Example:

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

Output:

Wednesday

Why Use switch Instead of if-else?

• Better readability when dealing with multiple conditions.

• More efficient in some cases as it directly jumps to the matching case.

Conclusion

• Use if-else when checking conditions that involve comparisons (>, <, >=, etc.).

• Use switch when comparing a single variable against multiple possible values.

Understanding these control flow statements will help you write efficient and clean JavaScript code!