What is SPA (Single-Page Applications)?

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Today, web applications are replacing the old desktop applications. They are more convenient to use, they are easy to update and not bound to the specific device. Basically there are are two main design patterns for web apps:

  1. Single-Page Applications (SPAs)
  2. Multi-Page Applications (MPAs)

Both patterns have their own pros and cons. When deciding between both patterns, it’s important to bear in mind your business goals and requirements. Let’s have a look at what are single page applications.

What’s a SPA?

Single Page Application(SPA) is a web application that fits on a single web page with dynamic actions without refreshing the page. You are using various SPA applications every day i.e. Gmail, Github, Facebook. It is just one page that you visit and use that page to dynamically re-render the content without ever requesting a second page to render by the server. In this, instead of navigating the page to another page, we just remove some elements from DOM (Document Object Model) and add new elements. Thus SPA provides a highly-interactive, very responsive and fast web page where we never have to wait, where things always happen and that is a great user experience.


Advantages of SPA:

  • Debugging with Chrome: SPAs are easy to debug with chrome as you can monitor network operations, investigate page components and data associated with it.
  • Fast and Responsive: SPA applications don’t update the entire page but only the required content. Most of the resources (HTML + CSS + Scripts) are only loaded once throughout the lifespan of an application.
  • Code Reusability: SPA application is easier to develop as the developer can reuse the same backend code for web application and native mobile application.
  • Caching Capabilities: SPA can cache any local storage effectively. If anyone has poor connectivity, then local storage can be synchronized with the server when connection allows.

Disadvantages of SPA:

  • Browser History: An SPA app doesn’t save users jump between states. This means that on clicking back button browser only takes the user to the previous page, not to the previous state of an application.
  • SEO Optimization: SPA provides poor SEO optimization as these applications operate on Javascript and download data on request from the client side. The URL doesn’t change and also different pages don’t have unique URL. Thus, most of the pages are not scanned by search bots for optimization of that page. Recently Google launched a new scheme to increase the SPA app SEO optimization.
  • Security Issues: SPA applications are less immune to cross-site scripting (XSS) attacks. Due to XSS, it enables attackers to inject client-side scripts into the application by other users.

Written by 

Rudar Daman Singla is the Trainee Software Consultant at Knoldus Software LLP. He has done B.Tech. from Jaypee University of Information technology, Waknaghat(Solan). He has good knowledge of languages C, C++, Java, Scala, HTML, CSS, PHP, Node and Angular. He is also interested in VFX. As a fresher, he always tries to explore the different type of software and tools.