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Building Single-Page Applications (SPAs) With Javascript Frameworks

May 31, 2023 1584 Views

Are you tired of traditional web applications’ clunky user experience and slow page loading times? Building Single-Page Applications (SPAs) with JavaScript frameworks is here to save the day! SPAs offer a seamless and responsive browsing experience. Hence, allowing users to navigate through different sections of an application without page refreshes. Using a JavaScript framework like the Sencha Ext JS framework simplifies the process.

In this blog, we will delve into the world of SPAs and focus on how to build them using the popular JavaScript framework Ext JS. We’ll address the challenges faced during SPA development and provide solutions that will equip you with the knowledge to overcome them. Let’s dive in and explore the exciting world of SPAs!

woman working with javascript library or javascript frameworks

What Is a Single Page Application?

A Single Page Application (SPA) is a web application that loads a single HTML page and dynamically updates its content using JavaScript. SPAs leverage frameworks like React or Angular to handle rendering and routing on the client side. Hence, enabling a smooth and responsive user experience without full page reloads. It also performs data binding.

How Do Single Page Applications Work?

Here’s a step-by-step breakdown of how SPAs typically work:

Client Request

The client (web browser) sends a request to the server to retrieve the SPA page.

Server Response

The server responds to the client’s request by sending the initial HTML file of the SPA.

SPA Page Arrives Either Empty or Pre-rendered

The SPA page can be sent in two ways. It can arrive as an empty HTML file containing only a root element (e.g., <div id=”app”></div>) and a script tag, or we can pre-render it with some initial content.

Script File Dynamically Injects HTML (If Needed)

If the SPA page arrives empty, the script file included in the HTML is responsible for dynamically injecting the necessary HTML content into the root element (e.g., <div id=”app”></div>). This dynamic injection can be done using JavaScript frameworks like React, Angular, or Vue.

Script Enhances the Markup and Applies Styles

Once the HTML content is injected into the root element, the script file enhances the markup and applies styles to the elements. We handle this step through the chosen JavaScript framework or library. This, in turn, manages the virtual document object model DOM and updates the actual DOM efficiently.

Asynchronous HTTP Requests and Data Population

At this point, the SPA is ready, and it can start making asynchronous HTTP requests to retrieve data from the server or other data sources. This data is then used to populate the content of the application dynamically. For example, a SPA for a social media platform may fetch posts, comments, or user information asynchronously.

Event Listeners and Client-Side History

The SPA sets up event listeners to respond to user interactions, such as clicks or form submissions. These event listeners trigger specific actions within the application. Hence, allowing for interactive and dynamic behavior.

Preloading Caches and Offline Capability

The SPA can start preloading caches to improve performance and provide offline capability. This means fetching and caching resources like images, scripts, or data that the application may need in the future.

Service Worker Installation

SPAs can take advantage of service workers, scripts that run in the background, and intercept network requests. Service workers allow for advanced features like push notifications, background synchronization, and offline functionality.

Man using different javascript frameworks & javascript libraries such as open source javascript framework

Single Page Application vs. Multi-Page Application

Multi-page Applications (MPAs)

  • MPAs are designed with HTML, CSS, and JavaScript and use server-side logic.
  • Each page in an MPA is a separate HTML file the server generates in response to user requests.
  • Server-side logic generates the HTML pages and handles data retrieval, processing, and rendering.
  • Navigation between pages involves full page reloads, as the server generates and serves a new HTML file for each page.
  • MPAs have good SEO compatibility since each page has its own URL and HTML content.
  • Code organization is typically more tightly coupled between the front end and back end.

Single Page Applications (SPAs)

  • SPAs are built using JavaScript and run entirely in the browser without server-side code execution.
  • They rely on client-side logic to dynamically render elements within a single HTML page.
  • SPAs fetch data from APIs and use JavaScript frameworks or libraries to handle data retrieval, processing, and rendering.
  • Navigation within a SPA is handled by client-side routing, updating the content dynamically without full page reloads.
  • SEO compatibility may be a concern with SPAs, but techniques like server-side rendering and prerendering can be employed to address this.
  • SPAs promote code reusability and can be more decoupled from the backend, allowing for separate development and reuse of frontend components.

It’s important to note that the distinction between MPAs and SPAs is not always black and white. Hybrid approaches can also exist, combining server-side rendering with client-side interactivity.

The choice between an MPA and a SPA depends on various factors, including the nature of the application, performance requirements, development resources, and desired user experience.

When to Choose Single Page Application?

Single Page Applications (SPAs) are a good choice when performance is a priority. With SPAs, the initial load time may be slower due to JavaScript framework overhead. However, the subsequent interactions within the application are faster due to dynamic content updates without full page reloads. Hence, resulting in a smoother user experience.

When to Choose Multi Page Application?

If your application primarily focuses on displaying information without requiring complex user interactions or frequent updates, a multi-page app can be a suitable choice. MPAs work well for simple, read-only requirements where users primarily consume content rather than actively interact or make frequent updates.

What Are the Features Of Single Page Applications?

Here are the three most common features of single-page applications:

Reducing Repetition

SPAs use the same code on multiple pages. Hence, reducing the repetition. It works in a way that the code is loaded once and then referenced from the same place. This is how it eliminates the need to reload it.

A Desktop Application-Like Experience

You can also use SPAs to provide the desktop application experience. This can be highly useful when our user wants to spend more time on a web page while accessing the content.

Building PWA Made Easy With SPA

SPAs can help us build progressive web apps that simplify the development process. It can help us provide an app-like experience to our users. This can be engaging, fast, reliable, and responsive.

Also Read: Creating Progressive Web Applications using Sencha Ext JS

an imaginary view of other frameworks for creating web apps in a model view controller through an open source javascript library

What Are the Pros And Cons Of Single Page Applications?

Here are some pros and cons of single-page applications.


Faster loading speeds

SPAs load initially as a single page, reducing the need for multiple page requests and resulting in faster loading times.

Capabilities for Caching

SPAs can leverage caching techniques to store and retrieve data from the local cache, reducing server requests and improving performance.

Improved User Experience

SPAs offer a seamless and interactive user experience with smooth transitions, real-time updates, and dynamic content rendering.


Slow in some Cases

SPAs relying heavily on JavaScript may experience slower initial loading times, especially if the JavaScript files are large or complex.

Issues With Search Engine Optimisation

SPAs initially face challenges with SEO since the content is dynamically rendered. However, techniques like server-side rendering or prerendering can mitigate these issues.

Website statistics

Tracking user engagement and website statistics can be more complex in SPAs due to the continuous loading of content within a single page.

What Is the Best Single Page Application Framework?

When it comes to determining the best Single Page Application (SPA) framework, it ultimately depends on the specific requirements and preferences of your project. However, Sencha Ext JS is indeed one of the popular and widely recognized JS frameworks for building SPAs.

Sencha Ext JS

Ext JS provides a comprehensive set of UI web components, robust data management capabilities, and extensive documentation and support.

With its rich feature set and enterprise-grade functionality, Sencha Ext JS is the most popular JavaScript framework that is often favored for complex and data-intensive applications.

Sencha - best javascript framework & one of the most popular javascript frameworks virtual DOM

What Are the Examples Of a Single Page Application?

Here are some popular examples:


Gmail is a popular email service that uses a single-page application approach to provide a seamless and responsive user interface for managing emails, contacts, and other features.


Netflix utilizes a single-page application to deliver a smooth streaming experience. Hence, allowing users to browse and watch movies, TV shows, and other content without page reloads.


Trello, a project management tool, employs a single-page application to provide a collaborative and real-time experience for managing tasks, creating boards, and organizing projects efficiently.

Are the Single Page Applications the Future of Web Apps?

Single Page Applications (SPAs) have gained significant popularity and have become a prominent approach in modern web application development. While it’s difficult to predict the future of web apps with certainty, several factors suggest SPAs will continue to play a significant role:

  • Enhanced User Experience
  • Mobile-Friendly and Responsive Design
  • High Performance and Efficiency
  • Foundation for building PWA Capabilities
  • High Developer Productivity and Code Reusability

While SPAs offer numerous advantages, it’s worth noting that they may not be suitable for all types of applications. Factors such as the project’s complexity, performance requirements, and SEO considerations may influence the choice between SPAs and other approaches.

SPAs have undoubtedly had a significant impact on the evolution of mobile app development and are likely to continue shaping the future of web applications.

What Businesses Need Single Page Applications?

Single Page Applications (SPAs) are beneficial for businesses that require highly interactive user interfaces and responsive web applications. E-commerce platforms can provide a seamless shopping experience, while social media platforms can offer real-time updates.

Collaboration tools, project management systems, and content-intensive websites can also benefit from SPAs for their dynamic and fluid user experiences.

businesses planning

Javascript Frameworks: Conclusion

Building Single-Page Applications (SPAs) with JavaScript frameworks has become a popular approach for developing modern web apps. JavaScript frameworks such as Ext JS, React, Angular, and Vue.js offer powerful tools and abstractions that simplify the web development process.

SPAs allow for seamless navigation, real-time updates, and improved performance by dynamically updating content without full page reloads. They are well-suited for mobile applications requiring interactivity, responsiveness, and a desktop-like experience. You must choose popular Javascript Frameworks for building user interfaces of SPAs.

Ext JS is one of the best JavaScript frameworks.

JavaScript Frameworks: FAQs

How Does a Single-Page Application Work?

SPA works by loading a single HTML file initially. Then, it dynamically updates content without page reloads using JavaScript.

What Is Single Page Application Framework?

A single-page application framework is a tool or library that provides structure and functionality for building SPAs.

What Is a Single-Page Application?

A Single-Page Application (SPA) is a web application that dynamically updates content without page reloads.

What Is the Difference Between Single-Page Applications and Web Applications?

Single-Page Applications (SPAs) are a type of web application, but not all web applications are SPAs.

Experience the power of Ext JS and elevate your web application development today!

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