Conditional statements in javascript (if, else if, else, switch)

In JavaScript, conditional statements are used to perform different actions based on different conditions.

1. if Statement

The if statement executes a block of code if a specified condition is true.

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

2. else Statement

The else statement executes a block of code if the condition in the if statement is false.

let age = 16;
if (age >= 18) {
    console.log("You are an adult.");
} else {
    console.log("You are a minor.");
}

3. else if Statement

The else if statement specifies a new condition to test if the first condition is false.

let age = 20;
if (age < 13) {
    console.log("You are a child.");
} else if (age >= 13 && age < 18) {
    console.log("You are a teenager.");
} else {
    console.log("You are an adult.");
}

4. switch Statement

The switch statement evaluates an expression, matches the expression's value to a case clause, and executes the associated block of code.

let day = 3;
switch (day) {
    case 1:
        console.log("Monday");
        break;
    case 2:
        console.log("Tuesday");
        break;
    case 3:
        console.log("Wednesday");
        break;
    case 4:
        console.log("Thursday");
        break;
    case 5:
        console.log("Friday");
        break;
    case 6:
        console.log("Saturday");
        break;
    case 7:
        console.log("Sunday");
        break;
    default:
        console.log("Invalid day");
}

Summary

if: Checks if a condition is true, and executes a block of code.
else: Provides an alternative block of code if the if condition is false.
else if: Allows testing multiple conditions.
switch: Compares an expression to multiple possible values (cases) and executes code for the matching case.

Comments and code readability

Loops (for, while, do...while)