Course Content

Introduction to JavaScript

1. JavaScript Fundamentals

About JavaScript Understanding JavaScript Syntax Challenge: Console Output in JavaScript Using Comments to Document Code Challenge: Write a Single-Line Comment Challenge: Write a Multi-Line Comment

2. Variables and Data Types in JavaScript

Understanding Variables in JavaScript Challenge: Define the Variable Using const for Constants Exploring JavaScript Data Types Working with null in JavaScript Introduction to Arrays Array Methods and Manipulation Challenge: Perform Array Operations

3. Performing Operations in JavaScript

Understanding Assignment Operators Mathematical Operations in JavaScript Assignment Operators in JavaScript Increment and Decrement Operators Challenge: Variable Operations Practice Comparison Operators in JavaScript Logical Operators Explained Challenge: Compare Variables in JavaScript Concatenating Strings in JavaScript Challenge: Build Sentences with JavaScript

4. Controlling Program Flow with Conditional Statements

Mastering if Statements in JavaScript Using else for Alternative Outcomes Applying else if for Multiple Conditions Challenge: Determine Sizes with Conditionals

5. Looping Through Data in JavaScript

Understanding the while Loop in JavaScript Using the do while Loop for Iteration Challenge: Print Numbers from 5 to 9 Mastering the for Loop in JavaScript Challenge: Console Tigers with Loops Breaking Out of Loops with break Skipping Iterations with continue Challenge: Stop and Skip in Loops

6. Functions in JavaScript

What Are Functions in JavaScript?Defining Functions in JavaScript Challenge: Write a Function – My Name Using Function Arguments Effectively Returning Values from Functions Challenge: Create a Sum Function Course Summary & Next Steps

Using const for Constants

Another way to define a variable in JavaScript is using the const keyword. The primary difference between let and const is that variables created using const cannot change their values, whereas using the let keyword allows changes to the variable's value.

javascript

Let's compare the behavior of variables using let and const. Take a look at the following example where we can change the value of the a variable:


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// A variable changing
let a = 5;
console.log(a); // Print the initial value of `a`

a = 10;
console.log(a); // Print the updated value of `a`

In contrast, let's examine the behavior of the b variable. We will encounter an error: TypeError: Assignment to a constant variable.


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// A constant cannot be changed
const b = 7;
console.log(b); // Print the initial value of `b`

// Attempting to reassign a `const` variable will result in an error
b = 8; // This line will throw an error: "TypeError: Assignment to constant variable."
console.log(b);

Usage

Constants are used as immutable variables. You can define a constant once and use it multiple times.

Constants provide data integrity while allowing for quick refactoring.

Note

Refactoring involves making structural changes to the code, such as modifying values, variable/function names, and more.

For example, consider maxHeight for site elements. You can release a site update by changing the maximum height of elements with just one modification in the code. However, it's important to note that you cannot change the maximum height during runtime, ensuring data integrity.


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const maxHeight = 250;
console.log(maxHeight - 15);
console.log(maxHeight - 12);
console.log(maxHeight - 5);
console.log(maxHeight - 13);
console.log(maxHeight - 22);
console.log(maxHeight - 52);

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Section 2. Chapter 3

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