JavaScript Basics

Introduction to JavaScript

JavaScript is a versatile programming language that is widely used in web development. It allows you to add interactive elements to web pages, making them dynamic and user-friendly.

What is JavaScript?

JavaScript is a high-level, interpreted programming language that is primarily used to create interactive effects within web browsers. It can manipulate HTML and CSS, making websites more interactive.

Setting Up Your Environment

Before you start coding with JavaScript, you need a code editor. Some popular options include:

• Visual Studio Code
• Atom
• Sublime Text

Ensure that you have a modern web browser like Google Chrome or Mozilla Firefox for testing your JavaScript code.

Understanding Variables

In JavaScript, variables are used to store data values. There are three ways to declare variables in JavaScript:

• var - Used before ES6, now mostly replaced by let and const.
• let - Block-scoped variable, introduced in ES6.
• const - Used for constants, ensuring the value cannot be reassigned.

Example:

            let name = "John";
            const age = 25;
        

Functions in JavaScript

Functions allow you to encapsulate code that can be reused. Functions in JavaScript are defined using the function keyword:

            function greet() {
                console.log("Hello, World!");
            }
            greet();
        

You can also create functions that take parameters and return values:

            function add(a, b) {
                return a + b;
            }
            console.log(add(5, 3)); // 8
        

Control Flow

Control flow allows you to control the execution order of code using conditional statements and loops. Common control flow statements include:

Conditionals

Conditionals check whether a condition is true or false and execute code based on that. Common conditional statements are if, else, and switch:

            if (age > 18) {
                console.log("Adult");
            } else {
                console.log("Minor");
            }
        

Loops

Loops allow you to repeat a block of code multiple times. The most common types of loops are:

• for loop
• while loop

Example of a for loop:

            for (let i = 0; i < 5; i++) {
                console.log(i);
            }
        

DOM Manipulation

JavaScript is often used to manipulate the Document Object Model (DOM), which represents the HTML structure of a web page. Here’s how you can select and modify elements:

            document.getElementById("myElement").innerHTML = "New Content";
        

Conclusion

JavaScript is an essential skill for web developers. With a good understanding of variables, functions, control flow, and DOM manipulation, you can start building interactive and dynamic websites.