A few years ago, when we used to have browsers with poor javascript performance, every page used to come from the server. For every click, there used to be a new request-response cycle from the browser to the server.

Today there are several frontend JavaScript frameworks available, that helps in creating an application as a single page application. User Only loads the application code(JavaScript, HTML, CSS) once, and when the user interacts with the application, JavaScript intercepts the browser events and rather than making a new server request, the client requests some JSON or performs an action on the server but the page that User sees is never completely wiped away.

A single-page application(SPA) is an app that works inside a browser and doesn’t require page reloading during use. Such applications are there in everyday use. These are, for instance: Gmail, Google Maps, Facebook.

Benefits of Single Page Applications

1. Production deployment and Versioning:

Single Page Applications are very easy to deploy in Production. It is mainly one index.html file, with a Javascript bundle and a CSS bundle.

Deploying the front-end as SPA has the advantage of versioning and rollback. It is done by versioning the build output.

2. User Experience:

In SPA, once the page is loaded for the first time, no more HTML gets sent over the network, rather data gets requested from the server(or posted to the server).This takes significantly less time and bandwidth than constantly sending HTML(as happens in case of traditional multi-page applications). This leads to an improved user experience due to less number of full-page reloads and better performance due to less bandwidth consumption.

3. Caching Capabilities:

A single-page app can cache any local data effectively. A SPA sends just one request to a server then stores the response it receives. Then it can use this data and work even offline. If a user has poor connectivity, local data can be synchronized with the server when the connection allows.

4. Debugging with Chrome:

It’s easy to debug a SPA with Chrome since such apps are developed on frameworks like Angular and React. These frameworks have their Chrome Developer tools that make debugging much easier than with MPAs. Besides, SPAs allow you to monitor network operations and investigate page elements and data associated with them.

Challenges

1. Search Engine Optimization:

SPAs provide poor SEO optimization. This is because single-page apps work on JavaScript and download data based on the request from the client-side. The URL doesn’t change and different pages don’t have their unique URL addresses. It’s hard to optimize these websites for search engines since most pages can’t be scanned by search bots.

2. Security issues:

Single-page apps are less immune to cross-site(XSS) scripting attacks than are multi-page apps. Using XSS, hackers can inject client-side scripts into web applications. One security issue is the exposure of sensitive data. If developers aren’t careful about what data is contained in the initial page load, they can easily send data that shouldn’t be exposed to all users. The whole of a SPA isn’t generally visible in the browser, which can provide a false sense of security. One more reason that SPAs can be insecure is missing access control at the functional level. Since developers move features and logic off the server and out to the client, it’s really easy to provide a client with access to functions that they shouldn’t be permitted to use.

3. Browser History:

SPA doesn’t save visitors’ jumps between states. A browser only takes the user to the previous page but not to the previous state in an app.

Single Page Application Development Frameworks

Single page application development needs frameworks that can handle the grand application architectures required for rich web apps.

Below are a few popular Frameworks for Single page application development.

1. Angular:

Introduced by Google, Angular is the most used framework for Single page application development. The extensive amount of built-in functionality allows developers to design and control applications for nearly every kind of task. It reduces code as well as allows the easy maintenance and scaling of applications over time.

2. React:

React is Introduced by Facebook and extensively used on Instagram. It is a powerful library that can handle most types of applications. Along with Flux (ReactJs’s application pattern for building user interfaces) React establishes a firm code base through web components to create web applications that would function wonderfully even in large-scale, constrained, or high resource-consuming environments.

3. Knockout:

Knockout works on the MVVM approach of application architecture that helps developers to better organize their code. It also allows the application and server synchronization while putting in necessary mechanisms to build large single-page web applications. The scalable architecture allows developers to design applications that can easily scale up or down depending on their user base. However, Knockout often requires few other libraries like RequireJs, DurandalJS, PagerJs to create a full-fledged single page application development framework.

4. Backbone:

The legacy single page application development framework is very popular amongst developers as it provides the necessary flexibility through the MVC model while also supporting collections that allow for variations to program architecture. By notably reducing the data tie-ups to the DOM, Backbone allows developers to create structural code that can be easily modified to reflect changes in the DOM. 

Major Features of Angular

1. Cross-Platform:

With Angular, Developers can create progressive web applications (PWA). PWA, using modern web capabilities, offers an app-like experience to the users.  Based on the needs, the Developer can deploy the app as native as well as progressive. The hybrid mobile SDK called Ionic can ship the apps to the app store and deploy the same to the mobile web as PWA.

2. Optimum Performance:

The loading time of Angular apps is faster than any other front end framework in the industry. It loads at a very good speed with any new component router. Further, As per user’s loading and rendering requirements the code gets split automatically. 

3. Less Code Framework:

Angular is a low code framework compared to the other front end technologies. Developers don’t need to write separate code to link the MVC layers. Also, the directives are isolated from the app code. These all together automatically minimize the development time.  

4. Two-Way Data Binding:

Two-Way Data Binding is another effective feature of Angular. The View layer and the Model layer stays in perfect synchronization. For every change in data in the model, the view reflects the change, similarly, for any change in view, the model is updated.

5. Dependency Injection:

The built-in dependency injection of Angular makes application development easier for developers. 

6. Directives:

Developers can create custom HTML tags serving as custom widgets with the help of directives. Developers can use these to decorate behavior-driven elements. As per the needs, DOM attributes can also be manipulated with the help of directives. 

7. Angular CLI (Command Line Interface):

Angular CLI is the command-line interface for Angular. It helps to automate the development workflow. The common Angular CLI commands like ng-new or ng-add supports the developers to discover ready-made features with ease.

Conclusion:

This article gives an overview of Single page applications(SPA) with Advantages and challenges. It also provides an insight into the most popular frameworks available for developing single-page applications, and features of Angular, one of the most used frameworks for developing SPA. We at Neova have the expertise for developing dynamic SPA using the latest frameworks like Angular and React.