What is DOM in JavaScript?
20 January, 2023
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Introduction
The Document Object Model (DOM) is a programming interface for HTML and XML documents. It represents the structure of a document as a tree of nodes, with each node representing an element or a piece of text. In JavaScript, the DOM can be used to access and manipulate the elements of a web page, such as by changing their content, styling, or position. This allows developers to create dynamic and interactive web pages that respond to user input and other events.
DOM Hierarchy
In JavaScript, the DOM is represented as a tree-like structure, where each node in the tree represents an element or a piece of text in the HTML or XML document. The topmost node in the tree is the "document" object, which represents the entire document. Each element in the document is represented by an "element" node, and a "text" node represents the text content of an element.
These element nodes are organized in a hierarchical structure, where each element can have child elements (represented as child nodes in the tree) and a parent element (represented as the parent node in the tree). This hierarchical structure is known as the "DOM hierarchy".
JavaScript allows you to navigate and manipulate the DOM by using properties and methods of the DOM nodes. For example, you can use the "childNodes" property to access the child elements of a specific element and the "appendChild()" method to add a new child element to an element.
Additionally, you can use the DOM traversal and modification methods like getElementById, getElementsByClassName, getElementsByTagName, querySelector, querySelectorAll to select elements in the DOM and make changes to them.
Popular DOM Methods
JavaScript provides a wide range of methods for manipulating the DOM. Some of the most commonly used methods include:
getElementById(id): returns the element with the specified ID.getElementsByTagName(name): returns a list of elements with the specified tag name.getElementsByClassName(name): returns a list of elements with the specified class name.querySelector(selector): returns the first element that matches the specified CSS selector.querySelectorAll(selector): returns a list of all elements that match the specified CSS selector.createElement(tagName): creates a new element with the specified tag name.createTextNode(text): creates a new text node with the specified text.appendChild(node): adds a new child node to an element.insertBefore(newNode, referenceNode): adds a new node before the specified reference node.removeChild(node): removes a child node from an element.replaceChild(newNode, oldNode): replaces an existing child node with a new node.addEventListener(event, function): adds an event listener to an element that triggers the specified function when the event occurs.removeEventListener(event, function): removes an event listener from an element.dispatchEvent(event): triggers the specified event on an element.
These are some of the commonly used DOM methods in JavaScript. Many other methods are also available, and new methods are added with new versions of JavaScript.
