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.

1let age = 18;
2if (age >= 18) {
3    console.log("You are an adult.");
4}

2. else Statement

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

1let age = 16;
2if (age >= 18) {
3    console.log("You are an adult.");
4} else {
5    console.log("You are a minor.");
6}

3. else if Statement

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

1let age = 20;
2if (age < 13) {
3    console.log("You are a child.");
4} else if (age >= 13 && age < 18) {
5    console.log("You are a teenager.");
6} else {
7    console.log("You are an adult.");
8}
9

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.

1let day = 3;
2switch (day) {
3    case 1:
4        console.log("Monday");
5        break;
6    case 2:
7        console.log("Tuesday");
8        break;
9    case 3:
10        console.log("Wednesday");
11        break;
12    case 4:
13        console.log("Thursday");
14        break;
15    case 5:
16        console.log("Friday");
17        break;
18    case 6:
19        console.log("Saturday");
20        break;
21    case 7:
22        console.log("Sunday");
23        break;
24    default:
25        console.log("Invalid day");
26}
27

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)