JavaScript DOM Basics: Complete Guide for Beginners Introduction The DOM (Document Object Model) is a programming interface that lets you interact with HTML elements using JavaScript. Understanding the DOM is essential for building interactive web pages. In this guide, you’ll learn: 1.What the DOM is 2.How to access and manipulate elements Step-by-step examples with explanations Common mistakes and best practices By the end, you’ll confidently use JavaScript to modify web pages dynamically. 1.What is the DOM? The DOM represents the structure of an HTML document as a tree of nodes. Each element, attribute, and text in HTML becomes a node in the DOM. Example HTML:

Hello World

Welcome to my website

JavaScript access: let title = document.getElementById("title"); console.log(title.textContent); // Output: Hello World Common Ways to Access DOM Elements By ID let header = document.getElementById("header"); By Class Name let items = document.getElementsByClassName("menu-item"); By Tag Name let paragraphs = document.getElementsByTagName("p"); Using querySelector / querySelectorAll let firstItem = document.querySelector(".menu-item"); let allItems = document.querySelectorAll(".menu-item"); Manipulating DOM Elements Change Text Content title.textContent = "Welcome to My Site"; Change Styles title.style.color = "blue"; title.style.fontSize = "24px"; Add / Remove Classes title.classList.add("highlight"); title.classList.remove("highlight"); Create New Elements let newPara = document.createElement("p"); newPara.textContent = "This is a new paragraph"; document.body.appendChild(newPara); Event Handling You can make pages interactive by responding to user actions: let button = document.getElementById("myBtn"); button.addEventListener("click", function() { alert("Button clicked!"); }); Mini Challenge Try to: Add a new list item to an existing

using JavaScript. Change the background color of a
when clicked. Best Practices Use querySelector/querySelectorAll for more flexibility Avoid inline JavaScript in HTML Keep DOM manipulation efficient (cache selectors) Test in different browsers for compatibility Conclusion Understanding the DOM is key to creating interactive web pages. With this guide: You can access, modify, and style elements dynamically You can handle events to create user interactions You’re ready to build more advanced JavaScript projects Learn JavaScript DOM basics with step-by-step examples, element selection, event handling, and practical tips for beginners.