JavaScript Web APIs Series: Document Object Model APIs
Tags: javascript, webdev, api, programming
Published: 2023-09-21 16:14:53

The Document Object Model, commonly known as DOM, is arguably the most useful part of JavaScript as it captures everything that JavaScript stands for, giving life to lifeless HTML web pages. However, there are more APIs related to the DOM, which allows you to build more interactive features into your applications.

In this article, you will explore the different APIs you can use alongside the DOM API to build more sophisticated UIs for your users.

## Prerequisites

The primary prerequisite to follow along with this article is to be familiar with the basics of JavaScript. Also, it'll be beneficial if you read the [introduction of the series](https://dev.to/olodocoder/javascript-web-apis-series-introduction-fjk).

Now that the introduction and prerequisites are out of the way, let's explore the JavaScript Web APIs under the Document Object Model category in the following sections.

## Document Object Model API

![doma](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/rj05chzm4pcwdcwexpc7.png)

Suppose you have the slightest knowledge of JavaScript. In that case, you're undoubtedly familiar with the DOM, an API that represents the webpage structure so that JavaScript can access and manipulate its style, content, and structure properly.

The following sections explore some of the things the DOM allows you to do.

### Dynamic Content Manipulation

The DOM API allows JavaScript to dynamically modify a webpage's content and structure. This is especially useful for creating interactive and user-friendly websites. For example, an online shopping website allows users to filter products by various criteria like price, brand, and category. When the user selects a particular filter, JavaScript can access the DOM, update the product list, and display only the relevant items without requiring a page refresh. This provides a seamless and efficient shopping experience.

### Form Validation

The DOM API can be used to validate user input on forms and provide real-time feedback to users, reducing errors and improving the overall user experience. For example, In an online registration form, JavaScript can leverage the DOM to validate whether the user has entered a valid email address, a strong password or selected all required fields. Using DOM manipulation, the form can instantly display error messages next to the fields with invalid inputs, helping users correct their mistakes without reloading the page.

### Smooth Page Transitions

The DOM API can be utilized to create smooth page transitions, adding visual appeal and enhancing the overall user experience during navigation. For example, In a [single-page application](https://developer.mozilla.org/en-US/docs/Glossary/SPA) (SPA), when the user clicks a link to navigate to a different section of the website, JavaScript can intercept the default link behavior, use the DOM to fade out the current content smoothly, load the new content dynamically, and then fade it back in. This creates an engaging and seamless transition between different sections of the website.

### Document Object Model API Implementation

As mentioned earlier, the DOM API allows you to access and modify a web page, and that includes but not limited to [height and width](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Examples#example_1_height_and_width), [image attributes](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Examples#example_2_image_attributes), [styling](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Examples#example_3_manipulating_styles), [events](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Examples#example_5_event_propagation), and [much more](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Examples).

The DOM is a huge object that allows you to bend a web page to your will as far as your creativity can go. That said, you can explore its [interfaces](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model#dom_interfaces), [SVG interfaces](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model#svg_interfaces), and [specifications](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model#specifications) on its MDN page.


## CSS Object Model API

![cssoma](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/1zy7fycowwd7hqhqjsyv.png)

The CSS Object Model API, commonly known as CSSOM, is a set of JavaScript APIs that allows you to read and manipulate CSS styles from your JavaScript code. Let's explore some things this API will enable you to build in the following sections.

### Real-time Styling Changes

The CSSOM allows JavaScript to interact with and modify CSS styles applied to elements in a webpage, enabling real-time style changes and visual effects. For example, a photo gallery can use CSSOM to allow users to hover over images to view additional information about each picture. JavaScript can manipulate the CSSOM to apply hover effects, such as increasing the image size and displaying a caption when the user hovers over an image.

### Media Query Manipulation

The CSSOM enables JavaScript to access and modify media queries, allowing websites to adapt their layout and design based on the user's device and screen size. For example, a responsive website can utilize CSSOM to check the screen width with JavaScript and then dynamically apply different styles, like adjusting font sizes, hiding certain elements, or repositioning content, based on whether the user is accessing the site on a desktop, tablet, or mobile device.

### Custom Animation Control

The CSSOM can be combined with other JavaScript APIs to control and customize animations on a webpage, providing a way to create unique and interactive animations. For example, consider a game website with a loading spinner. JavaScript can use the CSSOM to change the spinner's rotation speed, size, or color based on the game's loading progress, giving users a more engaging and entertaining waiting experience.

### CSS Object Model API Implementation

Implementing the CSSOM APIs is pretty straightforward, thanks to [extensive documentation](https://developer.mozilla.org/en-US/docs/Web/API/CSS_Object_Model) by MDN.

You can get a [detailed reference](https://developer.mozilla.org/en-US/docs/Web/API/CSS_Object_Model#reference) of the APIs, [tutorials](https://developer.mozilla.org/en-US/docs/Web/API/CSS_Object_Model#tutorials) on how to implement them, [specifications](https://developer.mozilla.org/en-US/docs/Web/API/CSS_Object_Model#specifications), and how to access the [browser compatibility](https://developer.mozilla.org/en-US/docs/Web/API/CSS_Object_Model#browser_compatibility)chart on its MDN page.

## Clipboard API

![cba](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/eyb36kt021wk3ua1wuda.png)

The Clipboard API allows you to implement dynamic copy, paste, and cut features in your JavaScript applications. To do this, it gives you access to the user's system clipboard so you can read and write to it easily. Let's explore some things you can build with this API in the following sections.

### Copy to Clipboard Functionality

The Clipboard API allows JavaScript to interact with the clipboard, making it possible to copy text or data to the user's clipboard. For example, a note-taking application can enable a user to select a piece of text or content. JavaScript can use the Clipboard API to copy the selected text to the clipboard, allowing the user to paste it into other applications or documents.

### Custom Copy Buttons

The Clipboard API enables developers to create custom copy buttons that simplify copying specific content from a webpage. For example, on a code-sharing platform, developers can create "Copy to Clipboard" buttons next to code snippets. When users click these buttons, JavaScript utilizes the Clipboard API to copy the code to the clipboard, allowing them to paste it into their projects efficiently.

### Secure Data Handling

The Clipboard API can be used to handle sensitive data securely by providing control over the clipboard contents. For example, in a secure messaging application, when a user receives a confidential message, JavaScript can use the Clipboard API to prevent the user from copying the message text to the clipboard, ensuring that sensitive information cannot be easily shared or leaked.

### Clipboard API Implementation

The Clipboard API is a pretty mature API making it straightforward to implement. Its MDN page covers [how to access the clipboard](https://developer.mozilla.org/en-US/docs/Web/API/Clipboard_API#accessing_the_clipboard), the [interfaces](https://developer.mozilla.org/en-US/docs/Web/API/Clipboard_API#interfaces) it uses under the hood, its [specifications](https://developer.mozilla.org/en-US/docs/Web/API/Clipboard_API#specifications), the [browser compatibility chart](https://developer.mozilla.org/en-US/docs/Web/API/Clipboard_API#browser_compatibility) which shows that it supports well over 95% of major web browsers, and much more.

## Fullscreen API

![fsa](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/3q76goml36mb779yblra.png)

The Fullscreen API is a set of methods that allow you to present an element in your application in fullscreen mode while hiding all the other elements until the fullscreen mode is turned off. Let's explore some of the things the Fullscreen API allows you to do in the following sections.

### Media Player Application

The Fullscreen API can be used in media player applications to provide users with an immersive viewing experience. When users click a fullscreen button within the media player interface, the application can request fullscreen mode using the Fullscreen API. This way, the media content (video or audio) will expand to fill the entire screen, removing any distractions and providing a more engaging experience for the user. Upon exiting fullscreen mode, the media player can resize to its original dimensions. This use case ensures that users can focus solely on their media content.

### Presentation or Slideshow Viewer

In presentation applications, like slideshow viewers, the Fullscreen API can be utilized to allow speakers to deliver their presentations in fullscreen mode. When the presenter clicks on a fullscreen button or presses a specific keyboard shortcut, the application can request fullscreen mode using the Fullscreen API. This ensures that the presentation takes up the entire screen, avoiding interference from other elements or applications. Once the presentation is over, the application can exit fullscreen mode, returning control to the regular presentation view.

### Immersive Web-based Games

Web-based games can benefit from the Fullscreen API to provide players with an immersive gaming experience. When players launch a game or trigger a fullscreen event in the game, the application can request fullscreen mode using the Fullscreen API. This will eliminate any browser UI and maximize the game's view, creating a more immersive and distraction-free gaming environment. Exiting fullscreen mode can be handled when the player chooses to quit the game or when specific game events require returning to regular browsing mode.

### Fullscreen API Implementation

The Fullscreen API is a mature API that supports all major web browsers and is pretty straightforward.

Its MDN page features details about its [methods](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#instance_methods), [properties](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#instance_properties), [events](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#events), [access control](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#controlling_access), [usage](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#usage_notes), [examples](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#examples), [specifications](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#specifications), [browser compatibility](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API#browser_compatibility), and much more. Read this [detailed guide](https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API/Guide) by MDN to explore the inner details of the API.

This example shows a [sample application](https://mdn.github.io/dom-examples/fullscreen-api/index.html) that shows how the Fullscreen API works.

## HTML Drag and Drop API

![hdada](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/yamwliaownha7ec30fdo.png)

The HTML Drag and Drop API is the magic behind drag and drop features in JavaScript applications. It allows users to hold and drag specific elements across the application interface based on what they want to do. In the following sections, let's explore some of the features you can build with this API.

### Task Management Application

A task management application can use the HTML Drag and Drop API to enable users to drag tasks from one category or status column to another. For example, users can drag tasks from the "To-Do" column to the "In Progress" column or from "In Progress" to "Completed." The application can utilize the Drag and Drop API events to track the dragged task's position, detect when it enters a drop zone, and update the task's status in the backend database. This provides users with an intuitive and interactive way to manage their tasks.

### Image Gallery Reordering

An image gallery application can utilize the HTML Drag and Drop API to allow users to rearrange the order of images within an album. Users can drag and drop images to reorder them, and the application can update the database to reflect the new order. The Drag and Drop API events, such as `dragstart`, `dragenter`, `dragover`, and `drop`, can be used to facilitate smooth and responsive reordering of images in the gallery.

### File Upload and Organization

In file management applications, the HTML Drag and Drop API can be utilized to enable users to upload files by dragging them from their local file system and dropping them into a designated drop area. The application can listen for the `drop` event, extract the files, and upload them to the server. Additionally, the API can support drag and drop within the application to allow users to organize their files by dragging them into different folders or categories.

### HTML Drag and Drop API Implementation

The HTML Drag and Drop API is mature and relatively straightforward to implement. You can do so by exploring its [concepts and usage](https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API#concepts_and_usage), [interfaces](https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API#interfaces), [examples](https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API#examples), [specifications](https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API#specifications) and more on its MDN page.

## Selection API

![sa](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/5cc966opx6xi2spbhsrf.png)

The Selection API allows you to access the part of the application interface immediately after the user selects it. This will enable you to build features that allow them to manipulate the selection anyhow they like. Let's explore some of the use cases of this API in the following sections.

### Text Analysis Tool

A text analysis tool can use the Selection API to enhance user interactions with selected text. When a user highlights or selects a portion of text, the application can use the Selection API to get the selected text's content and metadata, such as the start and end positions, the containing element, or any associated CSS styles. The tool can then display relevant options, such as dictionary definitions, translation suggestions, or the ability to copy the selected text to the clipboard. This API can provide valuable context and functionality to users analyzing and interacting with textual content.

### Annotation and Commenting System

In web-based collaboration platforms or document editors, the Selection API can be utilized to implement an annotation and commenting system. When a user selects a portion of text to leave a comment or annotation, the application can use the Selection API to capture the selected text's position and context. The system can then display a comment box or an annotation popup associated with the selected text, allowing users to add their comments, feedback, or notes directly to the relevant section of the content.

### Rich Text Formatting Toolbar

A web-based text editor or content creation tool can leverage the Selection API to enhance the user experience when applying rich text formatting options. When users select a portion of text, the application can use the Selection API to retrieve information about the selected text's properties, such as font size, font family, or formatting styles like bold, italic, or underline. The editor's toolbar can then update its state to reflect the selected text's formatting, allowing users to apply additional formatting or modify the existing styles easily. This API integration simplifies the process of formatting text and provides a more intuitive editing experience.

### Selection API Implementation

The Selection API is straightforward to implement as it only uses a few interfaces under the hood. Check out its MDN page for a deep dive into its [interfaces](https://developer.mozilla.org/en-US/docs/Web/API/Selection_API#interfaces) and [specifications](https://developer.mozilla.org/en-US/docs/Web/API/Selection_API#specifications) for more knowledge on how to implement it.

## Conclusion

And that's it! I'm sure you learned something new, no matter your level of experience using JavaScript to build web applications.

In this part of the series, you learned about the JavaScript web APIs that enable you to manipulate the webpage and everything within it as much as you like and the cool features you can build using them. You also explored how to implement them and the information you need to know through the linked resources in the implementation section of each API.

Finally, remember to follow me here on Dev and [Twitter](twitter.com/olodocoder). Thanks again for reading, and I'll see you in the next one! 👍