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Published Oct 19, 2023 ⦁ 10 min read
Web Coding 101: Learn JavaScript from Scratch Interactively

Web Coding 101: Learn JavaScript from Scratch Interactively

Introduction to Web Coding with JavaScript

JavaScript is the core programming language of the web. Learning JavaScript allows you to make dynamic, interactive websites and web apps. This guide will teach you JavaScript fundamentals through hands-on lessons and projects. No prior coding experience required - we start from the very basics. Follow along interactively right in your browser for the best learning experience.

What is JavaScript and Why Learn It?

JavaScript runs natively in web browsers and powers dynamic effects and interactivity. It is one of the core technologies of the web along with HTML and CSS. Over 97% of websites use JavaScript on the client-side for creating interactive web pages according to W3Techs. JavaScript skills allow you to make websites that accept user input, animate content, and fetch data. Knowing JavaScript opens the door to front-end and full-stack development careers. JavaScript is used beyond websites - also for apps, servers, IoT devices and more.

Some examples of dynamic website functionality powered by JavaScript include:

  • Dropdown menus and navigation
  • Interactive maps with custom markers
  • Form validation and submission
  • Drag and drop interfaces
  • Animated page transitions and effects
  • Fetching and displaying data from APIs
  • Charting and graphing data visually
  • 2D/3D games and physics engines

With JavaScript, you can take static HTML and CSS websites to the next level by adding logics, effects, visualizations, and real-time updates. JavaScript unlocks the true potential of web development.

JavaScript vs Python and Ruby

JavaScript is unrelated to Java - it has a similar name but very different usage. Other languages like Python and Ruby can be used for web programming. But JavaScript has the advantage of being the native language of the web with full browser support. Modern JavaScript (ES6+) has added many features to make it more robust and scalable.

Some key differences between JavaScript, Python, and Ruby:

  • JavaScript runs natively in browsers, others need compilation
  • Very fast runtime via JIT compilation in modern JavaScript engines
  • Asynchronous programming via promises and async/await
  • Dynamic typing with duck typing capabilities
  • Prototype-based object orientation instead of classes
  • First-class functions used extensively for callbacks, IIFEs, closures
  • Ecosystem of npm packages unmatched by other languages
  • Rising popularity for full-stack development with Node.js

While Python and Ruby have their strengths, JavaScript stands out as integral part of web development and enjoys seamless browser integration.

Getting Set Up for JavaScript Programming

All you need to start is a browser and text editor - no special software required. We recommend VS Code as a free, beginner-friendly code editor. Install Node.js to run JavaScript code outside the browser. Set up a live server for local development and testing. Chrome DevTools allow inspecting JavaScript on live sites.

Choosing an Editor and Installing Extensions

VS Code has great JavaScript support through extensions and built-in tools. Use the Live Server extension to instantly view code changes. Add Prettier for automatic code formatting as you type. Other popular free editors include Atom, Sublime Text, and Visual Studio. Premium editors like WebStorm offer more robust functionality.

Here are some recommended extensions for VS Code:

  • Live Server
  • Prettier - Code formatter
  • ESLint
  • Bracket Pair Colorizer
  • Code Spell Checker
  • JavaScript (ES6) code snippets
  • vscode-icons

These extensions provide features like live reloading, formatting, linting, enhanced syntax highlighting, and code auto-completion. Boost your productivity when writing JavaScript.

Setting Up Node.js and npm

Node allows executing JavaScript code on your local machine. It comes bundled with npm for installing JavaScript packages. npm contains over 1.5 million packages to add functionality. Use Node version manager (nvm) to easily switch Node versions. Set up a package.json file to manage dependencies for projects.

Node gives access to features like:

  • Running JavaScript outside the browser
  • Local web servers, APIs, scripts, automation
  • npm libraries and CLI tools
  • Build tools like webpack, Babel, ESLint, etc
  • Frameworks like React, Vue.js, Express, etc

While optional for basic learning, we recommend installing Node to unlock advanced JavaScript workflows.

JavaScript Syntax, Variables, and Data Types

Learn JavaScript syntax basics including semicolons, spacing, and comments. Declare variables with let, const, and var - understand the differences. Use data types like strings, numbers, booleans, arrays, and objects. Special values include null, undefined, NaN, and Infinity. JavaScript is a loosely-typed language with dynamic types.

Using Variables and Assigning Values

Declare variables with let and const, or var in older code. let can be reassigned, const cannot be reassigned. var is function scoped, let and const are block scoped. Assign values using = and reassign using =. Access variable values using the variable name.

For example:

// Declare variable with let  
let myVariable = 'Hello';

// Reassign variable
myVariable = 'World'; 

// Declare constant
const myConstant = 10; 

// Access value 
console.log(myVariable); // 'World'

This shows declaring a variable, reassigning it, declaring a constant, and logging the variable value.

let and const offer block scoping and should be preferred over var which can cause issues due to function scoping.

Working with Different Data Types

Strings use single or double quotes: 'hello' or "hello". Numbers can be integers, floats, hex, binary, etc. Booleans are true and false values. Arrays hold lists of data like [1, 2, 3]. Objects use key-value pairs like {key: 'value'}.


// String  
let greeting = "Hello world!";

// Number
let num = 10;

// Boolean  
let bool = true;

// Array
let list = [1, 2, 3]; 

// Object
let person = {name: 'John', age: 30}

JavaScript dynamically types values - you don't need to specify types on declaration.

Operators, Conditionals, Loops and Functions

Combine values and variables using arithmetic operators. Compare values with equality, relational and logical operators. Control program flow with if, else if, and else conditionals. Loop over code blocks with for, while, and do while loops. Wrap code into reusable functions and handle parameters.

Using Operators for Math and Comparisons

Arithmetic operators like +, -, *, /, % perform math operations. Assign values and concatenate strings with += and +. Compare equality with == and === (strict equality). Compare order and value with >, <, <=, and >=. Combine conditions using logical operators like && and ||.

For example:

// Arithmetic 
let sum = 1 + 2; // 3

// Concatenation
let greeting = 'Hello' + ' World'; // "Hello World"  

// Equality
1 == 1 // true
1 == 2 // false

// Strict equality 
1 === 1 // true
'1' === 1 // false

// Comparisons  
2 > 1 // true   

// Logical operators   
1 < 2 && 2 < 3 // true
1 < 2 || 2 > 3 // true

This demonstrates using different types of operators in JavaScript.

Controlling Logic Flow with Conditionals

Execute code blocks using if statements and else clauses. Chain multiple conditions with else if statements. Nest conditionals for complex logic flows. Use switch statements for multiple, discrete conditions. Ternary operator offers shortcut syntax for if/else.

For example:

let num = 5;

// If statement  
if (num > 0) {
  console.log('Positive number');

// If...else
if (num % 2 == 0) {
  console.log('Even number'); 
} else {
  console.log('Odd number');

// Else if 
if (num == 0) {
} else if (num > 0) {
  console.log('Positive number');  
} else {
  console.log('Negative number');

// Ternary operator
let parity = num % 2 == 0 ? 'even' : 'odd'; 

Conditionals allow controlling program flow based on logical conditions.

Practical JavaScript Projects

Apply your new JavaScript skills by building real-world projects. Projects reinforce your understanding through hands-on coding. Build things like an interactive quiz game, random quote generator, to-do app, and more. Get creative and think of useful JavaScript projects to expand your portfolio. Practice core skills like variables, functions, DOM manipulation, events, etc.

Project #1: Interactive Quiz Web App

Ask a series of multiple choice questions with feedback. Track correct and incorrect answers as quiz progresses. Show final score at the end, offer play again option. Use DOM manipulation to update questions, provide feedback. Store questions/answers in object or array, loop through them.

For example, you could:

  • Create question objects with properties for the question text, choices, and answer
  • Append question elements to the DOM for each question
  • Attach click handlers to choice buttons to check answers
  • Use conditional logic to provide feedback on correct/incorrect
  • Increment score variables to track correct answers
  • Allow restarting quiz by resetting variables and clearing previous questions

This project lets you practice:

  • Storing data in arrays/objects
  • Looping over data to generate quiz questions
  • Handling user input events like click
  • Updating HTML elements dynamically
  • Tracking game state like score
  • Resetting state to restart game

Project #2: Random Quote Generator

Display a new inspirational quote with each click of a button. Create array of quote objects with properties for text, author, etc. Select and display random quote object on button click. Allow tweeting and sharing quotes. Refresh quotes automatically every few seconds.

For example, you could:

  • Create quote objects with quote text, author, citation properties
  • Select random object from array on button click
  • Dynamically update DOM elements with new quote
  • Link to Twitter API to allow tweeting quotes
  • Use setInterval to periodically fetch and display new quote

This project allows practicing:

  • Generating random numbers
  • Selecting array elements using random index
  • Creating HTML elements dynamically
  • Handling click events to trigger actions
  • Using setInterval() for recurring actions
  • Integrating third party APIs like Twitter

Next Steps for Continuing your Web Coding Journey

You have completed the fundamentals - now apply your skills to build projects. Continue learning ES6+ features like arrow functions, classes, async/await. Dive into browser APIs like the DOM, Fetch, LocalStorage, Geolocation. Look into frontend frameworks like React, Vue.js and Angular. Explore fullstack tools like Node.js, Express, MongoDB and webpack. Check out our other courses on HTML, CSS, Programming and React.

Here are some top recommended resources for further learning:

  • Learn JavaScript - Continue interactive lessons and challenges to master modern JavaScript
  • Eloquent JavaScript by Marijn Haverbeke - Excellent book for intermediate JS programmers
  • JavaScript30 by Wes Bos - 30 day vanilla JS coding challenge
  • Codecademy, freeCodeCamp, Udacity - More online JS courses and tutorials
  • Javascript.info - Reference and guides for core language and browser APIs
  • Fireship.io - Short video tutorials on web development topics
  • Coding Train, Traversy Media - JavaScript video tutorial series on YouTube
  • JavaScript Weekly, JAMstacked - Weekly newsletters covering latest news

The JavaScript ecosystem is massive with so much to explore. Keep practicing, stay curious, and continuously grow as a developer. Most importantly, build projects and apply your skills to create something meaningful. Happy coding!

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