Learn JavaScript for Beginners – JS Basics Handbook

JavaScript is one of the most popular and widely used programming languages in the world. As the language of the web, JavaScript is an essential skill for any aspiring web developer looking to create dynamic and interactive websites. But even if you‘re not interested in web development, learning JavaScript can open up exciting possibilities in other domains like server-side scripting, game development, mobile app development, and more.

In this beginner‘s handbook, we‘ll introduce you to the fundamentals of JavaScript programming. No prior coding experience is required! Our goal is to demystify programming jargon and equip you with a solid foundation to write your first lines of JavaScript with confidence.

We‘ll cover everything from basic programming concepts to key language features like variables, data types, operators, conditionals, loops, functions, and objects. Along the way, you‘ll reinforce your understanding with plenty of examples, coding exercises, and mini-projects.

By the end of this guide, you‘ll have the skills to tackle simple coding challenges and a clear roadmap for your JavaScript learning journey ahead. Let‘s get started!

What is JavaScript?

JavaScript was created in 1995 by Brendan Eich, a programmer at Netscape, in just 10 days. The language was originally called Mocha, then LiveScript, before finally being renamed to JavaScript. Contrary to what its name suggests, JavaScript is not related to the Java programming language. The similar naming was a marketing move at the time, as Java was gaining popularity.

In the early days, JavaScript was used mainly for adding interactivity to web pages, like hover effects, form validation, and simple animations. But over time, JavaScript has evolved into a powerful and versatile programming language capable of so much more.

Today, JavaScript is a core technology powering interactive websites and web applications. It is supported by all major web browsers and is an essential part of the World Wide Web alongside HTML and CSS. JavaScript has also expanded beyond the browser, powering server-side applications with Node.js, mobile app development with frameworks like React Native, desktop apps with Electron, and more.

As a beginner learning to code, JavaScript is a fantastic choice. Its syntax is relatively simple and easy to learn compared to many other programming languages. JavaScript also provides instant visual feedback in the browser, making it highly engaging and rewarding to learn. And with its huge popularity and active community, you‘ll find no shortage of resources, libraries, and tools to support you on your learning journey.

Setting Up Your Development Environment

Before we start writing JavaScript code, let‘s set up our development environment. You‘ll need two key tools: a code editor and a way to run your JavaScript code.

For a code editor, we recommend installing Visual Studio Code (VS Code). VS Code is a free, open-source, and lightweight code editor that provides a great coding experience for JavaScript and many other programming languages. You can download and install VS Code from the official website: https://code.visualstudio.com/

Next, you‘ll need a way to execute your JavaScript code. One option is to use Node.js, an open-source JavaScript runtime that allows you to run JavaScript code outside of a web browser. Simply go to the Node.js website at https://nodejs.org and download the latest LTS version for your operating system.

Once you have VS Code and Node.js installed, you‘re ready to start coding! Create a new file in VS Code, save it with a .js extension (e.g. script.js), and use the integrated terminal to navigate to the file‘s directory and run it with the command: node script.js

Alternatively, you can also run JavaScript code directly in a web browser. Most modern browsers have a built-in JavaScript engine and developer tools that allow you to write and execute code. Simply open up the browser‘s console (in Chrome or Firefox, press Ctrl+Shift+J or Cmd+Option+J on a Mac) and start coding!

JavaScript Fundamentals

Now that our development environment is set up, let‘s dive into some core programming concepts in JavaScript.

Variables

Variables are used to store data in a program. You can think of them as labeled boxes that hold a value. In JavaScript, we use the let keyword to declare a variable:

let age = 30;

Here, we‘ve declared a variable named age and assigned it the value of 30. We can then access and use this value by referencing the variable name:

console.log(age); // Output: 30

JavaScript also provides two other keywords for declaring variables: const and var. Use const for values that won‘t change (constants) and var for variables with function or global scope. As a general rule, default to using let unless you have a specific reason to use const or var.

Data Types

JavaScript has several built-in data types, including:

• Strings: textual data enclosed in single or double quotes, e.g. "Hello, world!"
• Numbers: numeric data, either integers (1, 2, 3) or floats (1.5, 2.3)
• Booleans: logical values of either true or false
• Undefined: a variable that has been declared but not assigned a value
• Null: represents an intentionally empty value

JavaScript is a dynamically typed language, meaning we don‘t have to specify a variable‘s type when declaring it. The type is automatically inferred based on the value assigned.

let name = "Alice"; // String
let age = 30; // Number
let isStudent = false; // Boolean

Operators

Operators are symbols that perform operations on values and variables. JavaScript provides several types of operators:

• Arithmetic operators: perform mathematical calculations (+, -, *, /, %, **)
• Assignment operators: assign values to variables (=, +=, -=, *=, /=, %=)
• Comparison operators: compare two values and return a boolean (==, ===, !=, !==, >, <, >=, <=)
• Logical operators: combine or negate boolean values (&&, ||, !)

Here are some examples:

let x = 10;
let y = 5;

console.log(x + y); // 15
console.log(x > y); // true
console.log(x === "10"); // false

Arrays

An array is a special variable that can store multiple values in an ordered list. Arrays are created using square brackets [] with values separated by commas:

let fruits = ["apple", "banana", "orange"];

You can access individual elements in an array using their index (position) number, starting from 0:

console.log(fruits[0]); // "apple"
console.log(fruits[1]); // "banana"

Arrays have several built-in methods for adding, removing, and manipulating elements:

fruits.push("grape"); // Adds "grape" to the end
fruits.pop(); // Removes the last element
fruits.unshift("mango"); // Adds "mango" to the beginning

Control Flow

Control flow statements allow you to execute different code blocks based on certain conditions. The two main control flow structures in JavaScript are conditionals and loops.

Conditionals use if/else statements to perform different actions based on different conditions:

let age = 20;

if (age >= 18) {
console.log("You are an adult");
} else {
console.log("You are a minor");
}

Loops allow you to repeatedly execute a block of code. The for loop is commonly used to iterate over arrays:

let fruits = ["apple", "banana", "orange"];

for (let i = 0; i < fruits.length; i++) {
console.log(fruits[i]);
}

Functions

Functions are reusable blocks of code that perform a specific task. They help organize your code, make it more readable and maintainable, and allow you to reuse the same code in different parts of your program.

To declare a function, use the function keyword followed by the function name and parentheses (). The code to be executed is placed inside curly brackets {}:

function greet(name) {
console.log(Hello, ${name}!);
}

greet("Alice"); // Output: Hello, Alice!

Functions can accept parameters (input values) and return values using the return keyword. Arrow functions provide a more concise syntax for writing functions:

const add = (x, y) => {
return x + y;
};

console.log(add(3, 4)); // Output: 7

Objects

Objects are a fundamental concept in JavaScript. They are used to store collections of key-value pairs, representing real-world entities or abstract concepts.

Objects are created using curly braces {} with key-value pairs separated by commas. The key (also called property) is a string, and the value can be any valid JavaScript expression, including other objects and functions.

const person = {
name: "Alice",
age: 30,
isStudent: false,
greet: function() {
console.log(Hello, my name is ${this.name});
}
};

You can access object properties using dot notation or square bracket notation:

console.log(person.name); // Output: "Alice"
console.log(person["age"]); // Output: 30

Putting It All Together

Now that we‘ve covered the basics of JavaScript syntax and core concepts, let‘s build a simple program that puts it all together. We‘ll create a cash register application that can add items to a shopping cart, calculate the total price, apply discounts, and process payments.

Here‘s the code:

const cashRegister = {
  items: [
    { name: "Apple", price: 0.5 },
    { name: "Banana", price: 0.75 },
    { name: "Orange", price: 0.6 }
  ],
  cart: [],
  addItem: function(itemName) {
    const item = this.items.find(item => item.name === itemName);
    if (item) {
      this.cart.push(item);
      console.log(`${item.name} added to cart.`);
    } else {
      console.log(`${itemName} is not available.`);
    }
  },
  calculateTotal: function() {
    let total = 0;
    for (let i = 0; i < this.cart.length; i++) {
      total += this.cart[i].price;
    }
    return total;
  },
  applyDiscount: function(amount) {
    let total = this.calculateTotal();
    if (total > 10) {
      total -= amount;
      console.log(`Discount of $${amount} applied.`);
    }
    return total;
  },
  processPayment: function(amount) {
    const total = this.applyDiscount(2);
    if (amount >= total) {
      console.log(`Payment of $${amount} accepted. Thank you for your purchase!`);
      this.cart = [];
    } else {
      console.log(`Insufficient payment. Please provide $${total}.`);
    }
  }
};

// Add items to cart
cashRegister.addItem("Apple");
cashRegister.addItem("Banana");
cashRegister.addItem("Orange");

// Calculate total and process payment
const total = cashRegister.calculateTotal();
console.log(`Total: $${total}`);

cashRegister.processPayment(5);

This program demonstrates how to:

• Create an object (cashRegister) with properties and methods
• Use an array to store a list of items
• Define functions to perform actions (addItem, calculateTotal, applyDiscount, processPayment)
• Access object properties using dot notation
• Use control flow statements (if/else) for conditional logic
• Use a loop (for) to iterate over an array
• Call functions and pass arguments

Feel free to customize the items, prices, and discount amount to experiment with different scenarios!

Continuing Your JavaScript Journey

Congratulations on completing this beginner‘s handbook and writing your first JavaScript program! You‘re well on your way to mastering this powerful and versatile language.

As you continue your JavaScript learning journey, here are some recommended next steps:

1. Practice, practice, practice! The best way to solidify your understanding of JavaScript concepts is through hands-on coding. Solve coding challenges, build small projects, and experiment with different language features.

2. Dive deeper into JavaScript fundamentals. Topics like scope, hoisting, closures, callbacks, promises, and error handling are essential for writing robust and efficient code.

3. Explore the JavaScript ecosystem. Familiarize yourself with popular libraries, frameworks, and tools like React, Node.js, Express, and webpack. Understanding the JavaScript ecosystem will make you a more well-rounded and valuable developer.

4. Learn JavaScript design patterns and best practices. As you start writing more complex programs, it‘s important to structure your code in a clean, organized, and maintainable way. Design patterns provide proven solutions to common programming problems.

5. Contribute to open source projects. Once you‘re comfortable with the basics, consider contributing to open source JavaScript projects. It‘s a great way to gain real-world experience, learn from other developers, and give back to the community.

Remember, learning to code is a journey, not a destination. Stay curious, keep practicing, and don‘t be afraid to make mistakes. With patience and persistence, you‘ll be well on your way to becoming a proficient JavaScript developer.

Happy coding!