Introduction to JavaScript

Introduction to JavaScript

0%

1. Basic Concepts

Discover the fundamentals of JavaScript, including its purpose and syntax. Learn how to work with the console for output and use comments to organize and document your code. These foundational skills will prepare you for a deeper exploration of JavaScript's capabilities.

About JavaScript

Challenge: Console Output

Challenge: Single-line Comment

Challenge: Multi-line Comment

2. Variables and Data Types

Explore the building blocks of JavaScript by distinguishing between literals and variables. Understand the core data types, including `null` and arrays, and learn how to manipulate them using array methods.

Challenge: Defining the Variable

Data Types Overview

Challenge: Array Operations

3. Basic Operations

Learn how to manipulate JavaScript's data types through essential operations. Master assignment, mathematical operations, incrementing and decrementing, comparisons, logical operations, and string concatenation.

Mathematical Operations

Operations with Assignment

Increment and Decrement

Challenge: Variable Operations

Comparison Operations

Logical Operations

Challenge: Comparing Variables

String Concatenation

Challenge: Sentence Building

4. Conditional Statements

Discover how to control the flow of your programs with conditional statements. Master `if`, `else`, and `else if` to instruct JavaScript on making decisions and executing code based on different conditions.

else if

Challenge: Determining Size

5. Loops

Streamline your code by mastering JavaScript's looping structures. Explore `while`, `do while`, and `for` loops, and learn how to control their behavior using `break` and `continue`. Unlock the power of loops to perform repetitive tasks efficiently.

Challenge: Printing Numbers from 5 to 9

Challenge: Tigers

Challenge: Stopping and Skipping

6. Functions

Discover the power of functions in JavaScript. Learn how to define functions, work with arguments, and use the `return` statement to create reusable and efficient code. Mastering functions will enhance your ability to write clean and modular programs.

What is a Function?

Challenge: My Name

Course Content

Introduction to JavaScript

Introduction to JavaScript

else if

Now, let's explore a scenario where multiple conditions come into play:


              1234567891011121314151617
            
let a = 11;

if (a > 15) {
  console.log('greater than 15');
}

if (a > 10) {
  console.log('greater than 10');
}

if (a > 5) {
  console.log('greater than 5');
}

if (a > 0) {
  console.log('greater than 0');
}

In this example, the variable a is greater than 10, but other messages like "greater than 5" and "greater than 0" are also being printed. This isn't the desired behavior when you want to execute only one condition. The else statement wouldn't work well here due to multiple conditions.

Introducing else if

The else if construct provides a solution for selecting a specific code block within a series of conditions:

As you can see, the else-if statement is straightforward, with an if statement followed by it:

Let's apply this to our example:


              1234567891011
            
let a = 11;

if (a > 15) {
  console.log("greater than 15");
} else if (a > 10) {
  console.log("greater than 10");
} else if (a > 5) {
  console.log("greater than 5");
} else if (a > 0) {
  console.log("greater than 0");
}

Now, we've created a sequence of conditions. When at least one if condition becomes true, the chain is interrupted.

Note

This structure is useful when you only need one condition to be satisfied.

Adding else

You can also add an else statement after the condition chain. Let's modify our example:


              12345678910111213
            
let a = -61;

if (a > 15) {
  console.log("greater than 15");
} else if (a > 10) {
  console.log("greater than 10");
} else if (a > 5) {
  console.log("greater than 5");
} else if (a > 0) {
  console.log("greater than 0");
} else {
  console.log("No condition is satisfied");
}

Everything was clear?

Thanks for your feedback!

Section 4. Chapter 3

some-alt