What is DOM? Understanding DOM In JavaScript | JavaScript Tutorial #35 min read

In the past tutorials, we learned about conditionals in javascript (if, else, else if, while, for). if you have missed it you can access the complete javascript series here: JavaScript Tutorial. In this Tutorial, we will learn about DOM In JavaScript. How to work with DOM, Events In JavaScript, and More.

What is DOM?

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 objects, each object representing a part of the document (element, attribute, piece of text, etc.).

DOM allows you to manipulate the content, structure, and style of documents using programming languages ​​such as JavaScript. The DOM allows you to add, remove, or modify elements and attributes in your HTML or XML documents, as well as change the text and styles of elements.

To access the DOM in JavaScript, you can use the document object, which is the root of the DOM tree. You can then use the various methods and properties of the document object to navigate the DOM tree and access the document’s elements and attributes.

Below is an example of how to use the DOM to access and modify the content of an HTML document.

// Get the element with the id “my-heading”
var heading = document.getElementById(“my-heading”);

// Change the text of the element
heading.innerHTML = “Hello, World!”;

// Change the text of the element
heading.innerHTML = “Hello, World!”;

It is important to note that the DOM is not part of the JavaScript language, but rather a separate entity that is accessed and manipulated using JavaScript. The DOM is implemented differently by different web browsers, so it is important to test your code in multiple browsers to ensure that it works as expected.

Manipulating HTML elements with JavaScript

You can use JavaScript to manipulate HTML elements in a number of ways. Here are a few examples:

Accessing elements

You can use JavaScript to manipulate HTML elements in a number of ways. Here are a few examples:

To access an HTML element from JavaScript, you can use the `document` object and one of its methods, such as `getElementById`, `getElementsByTagName`, or `getElementsByClassName`. For example:

// Get the element with the id “my-element”
var element = document.getElementById(“my-element”);

// Get all the elements with the tag name “p”
var elements = document.getElementsByTagName(“p”);

// Get all the elements with the class name “my-class”
var elements = document.getElementsByClassName(“my-class”);

Modifying the content of an element

To modify the content of an element, you can use the` innerHTML` property. This property allows you to set the HTML content of an element. For example:

// Set the HTML content of the element
element.innerHTML = “Hello, World!”;

You can also use the `textContent` property to set the text content of an element. This property allows you to set the text content of an element without interpreting it as HTML. For example:

// Set the text content of the element
element.textContent = “Hello, World!”;

Modifying the attributes of an element

To modify the attributes of an element, you can use the `setAttribute` method. This method allows you to set the value of an attribute for an element. For example:

// Set the value of the “href” attribute
element.setAttribute(“href”, “https://www.example.com”);

You can also use the `getAttribute` method to get the value of an attribute. For example:

// Get the value of the “href” attribute var href = element.getAttribute(“href”);

Modifying the style of an element

To modify the style of an element, you can use the `style` property. This property allows you to set the CSS style of an element. For example:

// Set the color of the element to red
element.style.color = “red”;

// Set the background color of the element to yellow
element.style.backgroundColor = “yellow”;

It is important to note that you should use camelCase notation when setting style properties in JavaScript (e.g. `backgroundColor` instead of `background-color`).

Events In JavaScript

In JavaScript, an event is an action or event recognized programmatically. You can use events to trigger specific actions in your code when certain events occur. B. When a user clicks an item, hovers over an item, or submits a form.

To handle events in JavaScript, you can use event listeners. An event listener is a function that is called when an event occurs. You can attach an event listener to an element using the addEventListener method.

Here’s an example of how to handle a click event using an event listener.

// Get the element
var element = document.getElementById(“my-element”);

// Attach an event listener to the element
element.addEventListener(“click”, function() {
// This code will be executed when the element is clicked
});

You can also pass an event object to the event listener function, which contains information about the event, such as the type of event, the target element, and the coordinates of the event.

Here is an example of how you can use the event object to get the coordinates of a click event:

element.addEventListener(“click”, function(event) {
console.log(event.clientX + “, ” + event.clientY);
});

There are many different types of events that you can handle in JavaScript, such as `click`, `mouseover`, `submit`, `focus`, and `keydown`. You can find a complete list of events in the documentation for the `addEventListener` method.

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Tanmay Sinha

Founder & CEO at Mr Programmer

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