New to JS? This Beginner Tutorial Has You Covered

Introduction

Welcome to this beginner JavaScript tutorial! If you're completely new to programming or have no prior experience with JavaScript, then this guide is for you.

JavaScript has grown enormously in popularity and usage since it first appeared in 1995 as a simple scripting language for adding dynamic interactivity to websites. Originally created by Brendan Eich at Netscape, JavaScript now powers far beyond just web pages. Today it is used for full-stack web applications, mobile apps, game development, IoT devices, and more. Its flexibility as a lightweight, interpreted language that can run on both client and server makes JavaScript one of the most widely-used programming languages globally.

Over the course of this hands-on tutorial, you'll learn the core foundations of modern JavaScript (ES6 and beyond) through interactive examples and coding challenges. We'll cover fundamental language features like variables, functions, loops, conditionals, arrays, objects and more. You'll also learn how to manipulate the DOM to create dynamic web pages, handle events like clicks and hovers, validate forms, store data, and build interactive apps right in the browser.

With a focus on practical exercises for cementing each concept, this tutorial will give you a solid JavaScript base to start building your skills. Once you complete this guide, you'll have the knowledge needed to progress to more advanced JavaScript topics and tutorials here on Learn JavaScript. Let's get started!

Overview of JavaScript

Here are some key facts about JavaScript:

• Created by Brendan Eich at Netscape, now standardized across major browsers
• Can run on the client-side, server-side (Node.js), mobile apps, IoT devices, games, etc.
• Complementary role with HTML and CSS for web development
• Object-oriented language with first-class functions
• Lightweight, interpreted language that runs in browsers and app runtimes

Today, JavaScript powers full-stack web applications, cross-platform mobile app development with React Native, game development engines like Phaser, server-side programming with Node.js, and even machine learning libraries like TensorFlow.js. Its flexibility and ubiquity make it one of the most widely-used programming languages globally.

Who is This JavaScript Tutorial For?

This beginner JavaScript tutorial is ideal for:

• Complete programming newbies looking to learn their first language
• Those with some HTML/CSS experience wanting to add interactivity
• Self-directed learners seeking a structured JS curriculum
• Anyone wanting to gain core JS skills for front-end or full-stack development
• Those interested in learning practical JS for web, mobile, or games

No prior JavaScript experience is required to follow along! As long as you have an interest in coding and a willingness to learn through hands-on examples, this tutorial will teach you JavaScript fundamentals in a clear, engaging way. Let's get coding!

JavaScript Basics

To start using JavaScript, you first need to learn the building blocks of the language:

• Variables to store data
• Operators like arithmetic, comparison for math/logic
• Conditionals like if/else statements to control program flow
• Loops for repeating tasks
• Functions to reuse code
• DOM manipulation to dynamically modify web pages
• Events and event handlers to make things happen on clicks/hovers
• Including JS in HTML with <script> tags

We'll cover each of these concepts below with beginner-friendly introductions and interactive examples you can code yourself in the browser.

Core Language Constructs

Variables are containers that hold values in JavaScript. You declare a variable with let, const or var:

let myVariable = 'Hello'; 

JavaScript has several built-in data types like strings, numbers, booleans, etc. You can perform operations on variables using assignment, arithmetic, and string operators:

let x = 5;
let y = 10;
let z = x + y; // 15

To control program flow based on conditions, you use if, else if, and else:

let timeOfDay = 'morning';

if (timeOfDay === 'morning') {
  console.log('Good morning!');
} else if (timeOfDay === 'afternoon') {
  console.log('Good afternoon!');  
} else {
  console.log('Good evening!');
}

This if/else statement prints "Good morning!" if timeOfDay equals "morning".

And loops allow you to repeat tasks efficiently:

for (let i = 0; i < 5; i++) {
  console.log(i); // Prints 0, 1, 2, 3, 4
}

That covers some key language fundamentals! Now let's look at functions...

Functions

Functions are reusable blocks of code that perform specific tasks:

function greetUser() {
  console.log('Hello!'); 
}

greetUser(); // Prints "Hello!"

You can pass data into functions as parameters, and return values from them:

function double(x) {
  return x * 2;
}

let num = double(5); // num = 10

This is just a sample of the core concepts we'll cover. You'll learn by coding each one in real interactive examples!

The Document Object Model (DOM)

When a web page loads, the browser creates a DOM (Document Object Model) representing the page structure as nodes and objects.

JavaScript can access and manipulate the DOM to dynamically change web pages. For example:

• Select elements like buttons or forms
• Modify text, HTML attributes, styles
• Create, append, delete elements
• React to events like clicks, hovers, scrolling

Here's a taste of DOM manipulation with JavaScript:

Selecting and Manipulating Page Elements

Get a button by its ID:

const button = document.getElementById('myButton');

Change its text:

button.textContent = 'Click Me!';

Change CSS properties:

button.style.backgroundColor = 'blue';

This allows you to update UI elements, values, styles and more.

Traversing and Modifying the DOM Tree

Elements are structured in a tree with parent, child and sibling relationships.

Get the first child element:

const firstChild = parent.firstElementChild;

Append a new child element:

parent.appendChild(newElement); 

You'll learn more DOM manipulation by actually coding examples!

Events and Event Handlers

Events are actions that occur on a webpage like mouse clicks, hovers, key presses, and scrolling.

With JavaScript, you can detect events and run code in response using event handlers:

button.addEventListener('click', handleClick);

function handleClick() {
  // Do something on click
}

Some common events you'll use:

• click - Mouse click on an element
• input - Value changed on form fields
• submit - Form submitted
• keypress - Key pressed on keyboard
• scroll - User scrolled page

Here are some key concepts around handling events with JavaScript:

Using Events and Event Listeners

Detect clicks with onclick attribute handlers:

<button onclick="handleClick()">Click</button> 

Or use addEventListener() in JS:

button.addEventListener('click', handleClick); 

The handleClick function runs on click!

Stop event propagation with event.stopPropagation():

function handleClick(event) {
  event.stopPropagation();
  // Prevents event from bubbling
}

This gives you fine-grained control over event behavior.

Form Events and Validation

Validate forms before submission:

form.addEventListener('submit', validate);

function validate(event) {

  if(username.value === '') {
    alert('Please enter a username');
    event.preventDefault(); // Stop form submit
  }

  // Check other inputs
  
}

You can make live forms that provide real-time user feedback!

And there's a lot more to explore with events. You'll get hands-on experience with interactive examples.

Putting It All Together

Once you have a good grasp of the core concepts, it's time to put your skills to work building real applications and components with JavaScript. Here are some ideas:

• Build a calculator app
• Create a dynamic todo list
• Make an interactive photo gallery
• Develop simple browser games
• Design a form with live validation

Calculator App

Use DOM methods like getElementById() to select elements.

Attach click handlers to number buttons:

button.addEventListener('click', handleNumber); 

function handleNumber() {
  // Concatenate button value to output
}

Write a calculate() function to compute the result when operators like +, - are clicked.

Clear the output when a "C" (clear) button is clicked.

With these basics, you can build your own functional calculator entirely in JavaScript!

Dynamic Todo List

Use a form to get new todo items from the user.

Append new items to the DOM list:

const newTodo = document.createElement('li');
todosList.appendChild(newTodo);

Save todos array to localStorage:

localStorage.setItem('todos', JSON.stringify(todos));  

Load on page refresh:

const storedTodos = JSON.parse(localStorage.getItem('todos'));

Check off completed, delete items, etc!

This combines many core skills into a complete todo list app.

These examples demonstrate how you can apply your new JavaScript skills to build interactive apps and components. Let's recap what you learned.

Conclusion and Next Steps

In this beginner JavaScript tutorial, you learned the foundations of the language:

• Core concepts like variables, functions, conditionals and loops
• DOM manipulation for dynamically updating web pages
• Handling events like clicks and hovers
• Building real interactive apps in the browser

You now have fundamental JavaScript skills to add interactivity to sites.

To take your learning further, Learn JavaScript offers advanced tutorials on topics like:

• ES6 arrow functions, classes, let/const
• Asynchronous programming with Promises
• AJAX and APIs
• React for complex UIs
• Node.js for server-side JavaScript

With continued practice and the right resources, you'll master JavaScript in no time!