Course Content

Introduction to JavaScript

1. Getting Started

First Javascript Console Application Challenge: Showing some Output Challenge: Outputing Multiple Lines Dealing with Numbers Challenge: Working with Numbers Challenge: Calculating the Speed of a Car Challenge: Calculating Area of a Trapezium Outputting Multiple Values Challenge: Consoling Meaningful Output How to Use Comments in Javascript?Challenge: Adding a Comment Multi-Line Comments Challenge: Commenting out Code What Is JavaScript anyway?

2. Manipulating Data

Storing Data Challenge: Declaring a Variable Challenge: Accessing Data From a Variable Challenge: Fixing Variable Names Challenge: Reassigning a Variable Constants Challenge: Declaring & Using Constants Performing Arithmetic On Variables Challenge: Making a Salary Calculator Challenge: Adjusting Salary with a Bonus Exploring Primitive Data Types Challenge: Declaring a Boolean Value How different Data Types Interact Challenge: Concatenating Strings Challenge: Creating User Profile & Activity Details

3. Conditional Statements

Comparison Operators Challenge: Checking Age Eligibility The `if` Statement Challenge: Weather-Based Outfit Recommender Challenge: Even or Odd Nested Conditional Statements The `else` Clause Challenge: Improving Even or Odd Checker Challenge: Temperature Advisor The `else if` Clause Challenge: Grade Categorizer ` AND` Logical Operator Challenge: Checking if a Number is Even and Positive OR Logical Operator Challenge: Accessing Control System

4. Mastering Functions

What Are Functions?Challenge: Simple Function Challenge: Calculating the Speed of a Car Scopes Passing Data into Functions Challenge: Fixing the Speed Function Challenge: Improving the Grade Categorizer Task: Defining a Compound Function Returning Data from Functions Default Values Challenge: Email Auto-Responder with Default Parameters

5. Exploring Arrays

What Are Arrays?Challenge: Defining An Array Challenge: Indexing Adding Values to an Array Challenge: Pushing Elements to an Array Removing Elements from an Array Challenge: Practicing `pop` & `shift`The `length` Property Challenge: Counting Elements The `includes` Method Challenge: Searching for Animals in the Zoo

6. Discovering Loops

The `for` Loop Task: Printing a Sequence The `while` Loop Challenge: Printing Fibonacci Sequence The `do-while` Loop Challenge: Random Multiple of 7 Using Loops with Arrays Challenge: Finding the Average Price of Items Summary

What Are Arrays?

Definition

An array is simply an ordered collection of variables.

Defining an Array

The general syntax of defining an array is:

js

We can declare an empty array as well:


python

Arrays are useful when we need to store multiple values in a single variable instead of creating separate variables for each value.

This makes data easier to organize and manipulate. For example, we can store the names of the class students in an array:

We can output all the elements of an array by simply using it's name in a console.log statement:


              12345
            
let students = [ "Emma", "Alex", "Chris" ];
console.log(students);

let emptyArray = [];
console.log(emptyArray);

Indexing

We can access an element at a specific position in the array by indexing.

The syntax for indexing is:

js

Here arrayName is the name of the array, and index refers to the position of the element in the array.

The index values start from 0, which means the first element always has an index 0.


              1234
            
let students = [ "Emma", "Alex", "Chris" ];
console.log(students[0]); // Output: Emma
console.log(students[1]); // Output: Alex
console.log(students[2]); // Output: Chris

Using an invalid index returns undefined:


              123
            
let students = [ "Emma", "Alex", "Chris" ];
console.log(students[-1]); // Output: undefined
console.log(students[4]); // Output: undefined

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Thanks for your feedback!

Section 5. Chapter 1

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Course Content

Introduction to JavaScript

1. Getting Started

2. Manipulating Data

3. Conditional Statements

4. Mastering Functions

5. Exploring Arrays

6. Discovering Loops

What Are Arrays?

Definition

An array is simply an ordered collection of variables.

Defining an Array

The general syntax of defining an array is:

js

We can declare an empty array as well:


python

Arrays are useful when we need to store multiple values in a single variable instead of creating separate variables for each value.

This makes data easier to organize and manipulate. For example, we can store the names of the class students in an array:

We can output all the elements of an array by simply using it's name in a console.log statement:


              12345
            
let students = [ "Emma", "Alex", "Chris" ];
console.log(students);

let emptyArray = [];
console.log(emptyArray);

Indexing

We can access an element at a specific position in the array by indexing.

The syntax for indexing is:

js

Here arrayName is the name of the array, and index refers to the position of the element in the array.

The index values start from 0, which means the first element always has an index 0.


              1234
            
let students = [ "Emma", "Alex", "Chris" ];
console.log(students[0]); // Output: Emma
console.log(students[1]); // Output: Alex
console.log(students[2]); // Output: Chris

Using an invalid index returns undefined:


              123
            
let students = [ "Emma", "Alex", "Chris" ];
console.log(students[-1]); // Output: undefined
console.log(students[4]); // Output: undefined

Everything was clear?

Thanks for your feedback!

Section 5. Chapter 1

Introduction to JavaScript

What Are Arrays?

Defining an Array

Indexing

1. What is an array in JavaScript?

2. Which of the following is the correct way to declare an array?

3. What does the following code output?

4. What will be the output of the following code?

Introduction to JavaScript

What Are Arrays?

Defining an Array

Indexing

1. What is an array in JavaScript?

2. Which of the following is the correct way to declare an array?

3. What does the following code output?

4. What will be the output of the following code?