Introduction to JavaScript

JavaScript, or as you’ll often see it referenced as “JS," is a versatile and powerful programming language used primarily for web development to create dynamic and interactive user experiences.

It can manipulate HTML and CSS to update content, apply styles, control layouts, perform complex calculations, validate user inputs, and even fetch server data.

JavaScript is one of the World Wide Web's three core technologies, alongside HTML and CSS. It is indispensable for creating modern interactive websites.

By the end of the series, you’ll have a good grasp of the fundamental concepts of JavaScript, which will prepare you to start building web applications.

But first, how do we write JavaScript?

Where to Write JavaScript

JavaScript can be written and executed in various environments, each offering unique features. But in this series, we will focus on three different environments:

Browser Console

The browser console is a built-in tool in modern web browsers. It provides a quick and convenient way to test JavaScript code. Developers can write and execute code snippets directly within the browser.

How to Open the Browser Console:

Chrome: Press Ctrl+Shift+J (Windows/Linux) or Cmd+Option+J (Mac).
Firefox: Press Ctrl+Shift+K (Windows/Linux) or Cmd+Option+K (Mac).
Edge: Press F12 and navigate to the "Console" tab.
Safari: Press Cmd+Option+C (Mac).

The browser console is an essential tool for developers because it is particularly useful for debugging and testing small pieces of code in real time.

A screenshot of developer tools open on the console tab. Red rectangle highlighting the tab.

CodePen

CodePen is an online code editor and learning platform that allows you to write HTML, CSS, and JavaScript code snippets, known as "pens," and see the results instantly. It's an excellent tool for experimenting with code and sharing your work with others.

How to Use CodePen:

Go to CodePen.io.
Click on "Create" and select "Pen".
Write your HTML, CSS, and JavaScript in the respective panels.
View the output in the preview panel.

CodePen's live preview feature is invaluable for seeing changes in real time, making it a great platform for learning and experimenting with web development.

VSCode (Visual Studio Code)

Visual Studio Code (VSCode) is a highly popular, free code editor developed by Microsoft. It is widely used for JavaScript development due to its extensive features, including syntax highlighting, debugging, version control, and a vast library of extensions.

How to Set Up VSCode for JavaScript:

Download and install VSCode.
Open VSCode and create a new file with a .js extension.
Write your JavaScript code in the editor.
Connect the JavaScript file to the HTML file by including a <script> tag in the HTML file.

Assuming you created a file called script.js here's how to connect a JavaScript file to an HTML file in VSCode:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript Example</title>
</head>
<body>
    <h1>Hello, JavaScript!</h1>
    <script src="script.js"></script>
</body>
</html>

Don’t worry about this too much for now because we will cover it in more detail later.

Why Learn JavaScript?

JavaScript is a fundamental language for web development, enabling you to create interactive and dynamic websites. Here are some compelling reasons to learn JavaScript:

Dynamic Content: JavaScript allows you to modify HTML and CSS dynamically, creating interactive, dynamic web pages that can change content, styles, and layout without reloading the page.
User Interaction: With JavaScript, you can capture and respond to user actions such as clicks, key presses, and form submissions, enhancing the user experience.
Server Communication: JavaScript enables you to fetch data from servers asynchronously using technologies like AJAX and APIs, allowing for real-time updates and seamless data integration without refreshing the page.
Web Applications: JavaScript is the backbone of many modern web applications. Frameworks and libraries such as React, Angular, and Vue.js rely on JavaScript to build complex, high-performance web applications that run entirely in the browser.

Learning JavaScript opens up numerous opportunities in web development, from building simple web pages to developing sophisticated web applications. This skill is in high demand and continues to grow as the web evolves.

Next, we will explore the Document Object Model (DOM), a crucial concept for interacting with web pages using JavaScript. The DOM represents the structure of a web page, allowing you to access and manipulate its elements programmatically. Understanding the DOM is essential for creating dynamic and interactive web pages.