Single Page Application

What is a single-page application?

A single-page application (SPA) is a website or application with only one page. Single-page applications dynamically rewrite new data onto the current web page rather than loading new pages to display new content.

SPAs load only once during the initial page load. This often contributes to improved application performance, reduced development time, and fewer server requests.

Software developers and organizations use application server software to quickly build and deploy single-page applications. These application servers provide a framework for building and deploying web applications and typically include security features, transitions, and diagnostic capabilities, making them an all-in-one tool for developers.

Advantages of single-page applications

Single-page applications are a popular choice for many developers because of the advantages they can provide. The pros of single-page applications include: 

• A better user experience (UX) overall: Since SPAs only load once and the content updates dynamically, the user experience is smoother and more responsive than multi-page applications. Users tend to be more engaged than they would be if they had to repeatedly wait for content to load.  

• Improved load speed: A single-page application only loads the information necessary rather than loading entire pages from scratch. Load speed decreases significantly due to using one page instead of multiple. 

• Faster development: Developers can save time by focusing on one page and its contents rather than building an extensive application with many pages. Using a variety of APIs with SPAs can also improve the developer experience, allowing them to work on the front and back end of the application efficiently. APIs make it easier for developers to pull the content they need from the server.
• Easier debugging and testing: SPAs can be easier to debug because the codebases tend to be modular, which keeps elements separate and independent. Some SPA frameworks also have robust developer tools to further simplify debugging and testing.

Disadvantages of single-page applications

While single-page applications provide numerous benefits, there are potential challenges to going the SPA route. Potential cons of SPAs include:

• Search engine optimization (SEO) and indexing challenges: It’s difficult for search engines to index SPAs since all the content loads on one page. While many search engines have found ways to index SPAs better, SEO performance and optimization can still be a concern, depending on the nature of the page and desired search rankings. 

• JavaScript access issues: SPAs rely heavily on JavaScript to dynamically load content onto the page. If an individual voluntarily disables JavaScript or an IT team disables JavaScript for the employees in an organization, SPAs won’t load and work properly. This creates accessibility issues and, ultimately, a poor user experience. 

• Navigation challenges: Users can quickly review their page history on multi-page sites with the forward and backward buttons. These buttons don’t function the same way on an SPA, and users may need to manually navigate back to where they’d like using menu buttons or other drag-and-drop features.
• Website analytics considerations: Users can add code to each page for more precise tracking on multi-page websites. However, there’s only one page to track on an SPA, which may affect the accuracy of the data. Without a solid analytics approach, it may be challenging to determine which content is most appealing to users or where they are dropping off in the customer journey. 

Examples of single-page applications

Some examples of well-known single-page applications that people use every day are:

• Gmail: When a user opens Gmail, the application loads on one page. All actions in Gmail (e.g., opening emails, composing messages, and receiving new emails) happen dynamically, meaning users don’t have to refresh the page to complete these tasks. The header and sidebar never change in Gmail after it loads the first time. 

• Netflix: Users can navigate through different titles, watch trailers, and manage their accounts after loading the Netflix interface once. The consistent Netflix header and navigation do not change as users move through the streaming platform. 
• Trello: Trello, a well-loved project management tool known for its Kanban-style functionality, is an excellent example of a single-page application. This tool allows users to add, modify, and move cards across a board through drag-and-drop functionality without refreshing the page. 

Common frameworks for single-page applications

Teams should consider the goals of their project, the scope of the work, the developers’ skills, and the overall desired functionality before choosing a particular SPA framework to work with. Popular SPA frameworks include:

• AngularJS: AngularJS was developed by Google and is an open-source JavaScript-based framework for developing SPAs. It’s known for its effectiveness, simplicity, and flexibility, all of which help developers create fast web applications. It also offers Document Object Model (DOM) rendering. 
• Ember.js: Ember.js is an open-source JavaScript framework known for its ability to build rich user interfaces across various device types. 
• React: React is a free and open-source JavaScript library maintained by Meta and a community of individuals. React helps developers create reusable UI components following a component-based architecture. 
• Vue.js: Often called Vue, Vue.js is a JavaScript framework known for its seamless integration capabilities and simplicity. Developers leverage Vue to create interactive and responsive user interfaces for SPAs.

Single-page application vs. multi-page application

A single-page application (SPA) is a web application that loads a single page and dynamically displays new content to the user rather than reloading the entire page. SPAs use JavaScript to fetch data and content and update parts of the page based on how the user interacts with the page.

A multi-page application (MPA) is a traditional web application where each user interaction results in a full-page reload. Navigating between different sections or views involves fetching new pages from the server rather than fetching smaller pieces of content. 

Learn about application and web servers and their critical role in web application development and deployment.