The Document Object Model (DOM) is an application programming interface (API) for HTML and XML documents.
It defines the logical structure of a webpage and provides a structured tree of objects (nodes) representing all elements so programs can access and manipulate them.
In essence, the DOM allows scripts (like JavaScript) to dynamically change a page’s content, structure, or style after it is loaded.
How it works
The DOM represents an HTML document as a hierarchical tree of nodes (e.g., the document, <body>, paragraphs, links). Each node is an object with properties and methods.
By using DOM methods (for example, document.querySelectorAll(“p”) to get all <p> elements), a developer can traverse or update parts of the page.
The browser provides this DOM interface, and JavaScript (or other languages) uses it to respond to user actions and update the UI.
Why is DOM important?
The DOM is crucial for interactive web pages. It enables features like live content updates, form validation, dynamic styling, and interactive interfaces on the Web.
For example, when a user clicks a button and a script hides an element or fetches new data to display, that’s done by manipulating the DOM.
Understanding the DOM is foundational for web development because it is how your code “connects” to the page content.
DOM use cases
Common uses of the DOM include:
- Dynamic content: Inserting, removing, or modifying HTML elements via scripts (e.g., adding a new list item to a menu without reloading the page).
- Event handling: Attaching event listeners to DOM elements to handle clicks, key presses, etc., and updating the interface in response.
- Web app frameworks: Libraries and frameworks (like React or Angular) abstract away direct DOM manipulation but ultimately rely on the DOM API under the hood to update the view.