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Progressive Web Applications (PWA) and Single-Page Applications (SPA) are two fundamentally different digital solutions that the modern web development world offers, among many other cutting-edge tools and techniques. PWA and SPA are solutions that developers frequently use since they are both straightforward in design, relatively simple to promote in search engines, and offer forward-thinking user features. Let's examine parts of creating these web apps in depth, while contrasting their key characteristics and fundamental differences.

What is a Single Page Application (SPA)?

Generally, a single-page application loads only one web page and - when new content has to be displayed - uses JavaScript APIs like XMLHttpRequest and Fetch to update the page's body content. In a SPA, all necessary HTML, JavaScript, and CSS code is either retrieved by the browser, or is added to the site as needed, using appropriate resources that are reliably loaded. Typically, this occurs in response to the user's actions. This enables users to interact with websites without having to download entire new pages from the server; potentially improving performance and creating a more dynamic user experience.

However, there are some tradeoff disadvantages, such as increased effort needed for SEO, state maintenance, navigation, and meaningful performance monitoring. These, and many more, will be discussed in detail in the article.

The Technology of SPA (Single Page Application)

Single-page application architecture is pretty straightforward. It contains server-side and client-side technologies, as depicted in the image below.

Image source: Monocubed

The HTML file and its components are empty when a web browser requests a web page from a server since they do not contain any data. The SPA returns an HTML file with placeholder elements and specific files containing JavaScript and CSS codes. The server is queried for content when the browser executes the JavaScript files and the HTML code for the web browser receives this content. The heart of single-page applications lies in these JavaScript files. Instead of requiring a page refresh or reload, they dynamically update the DOM in the web browser.

There are three choices:

1. Server-Side Rendering (SSR)

In server-side rendering, browsers request HTML files from servers. The server gathers all the required information, extracts the program, and generates the application's HTML file. The users view the content that is available. The single-page application framework executes additional activities, constructs a virtual DOM, and adjoins the events. Then, the program is available for use. You might choose server-side rendering because it benefits from the speed of a single-page web application and does not burden users' browsers.

2. Client-Side Rendering (CSR)

In client-side rendering, the browser makes a request to the server for an HTML file. The server responds with a straightforward HTML file that includes linked scripts and styles. While JavaScript is running, the users may view a blank website or a specific loader graphic. The software gathers the information, creates the views, and inserts it into the DOM. Then the program is available for use. This may be a better option for websites that look plain. However, you must remember that interpreting data on the client-side requires a lot of resources from the device, which could cause the user's browser to get overloaded. 

3. Static Site Generators (SSG)

In static site generators, the browser queries the server to deliver the HTML file. The server then quickly responds with an HTML file that has already been organized. Customers view the page. The software creates views, draws the data, and inserts it into the DOM. Then the program is available for use. Static site generators (SSG) are a quick and solid solution, but keep in mind that they would not be your best choice if your website had live content as they are more useful for static sites.

What is the best framework for SPAs?

A single-page web application framework is a type of web framework that offers a base for creating SPAs. These SPA frameworks have a collection of tools and libraries that help developers avoid writing repetitive code. They also offer automated data binding, URL routing, HTML element modification, and unit testing. Numerous tools are integrated into a single-page application framework to speed up the development process. These frameworks include ready-to-use components, automated repetitive coding tasks, HTML and AJAX support, URL routing, data caching, security vulnerability protection, and increased performance.

Below is a list of the most popular web frameworks for developing single-page web applications.

1. React.js

Image source: vectorstock.com

A popular high-performance library for UI development is React.js. It is utilized on numerous well-known social media platforms, including Facebook, Instagram, etc.. Previously, utilizing server-rendered HTML to develop applications was the norm. Every time a user interacted with the system, a new request was sent, which led to the loading of a fresh page. This led to a slow loading time, which caused poor performance and a bad user experience. React employs Virtual DOM, and this "Virtual DOM" is regarded by developers as React's best advantage. React.js is preferred as the best framework for SPA development because it is;

  • Lightweight
  • Virtual DOMs
  • Highly scalable and flexible
  • Object-oriented paradigm

2. Vue.js

Image source: vectorstock.com

The model-view-view-model (MVVM)-based front-end JavaScript framework Vue.js is used to create user interfaces, SPAs, and web applications. Declarative rendering, component composition, and the view layer are the framework's main areas of concentration. Vue.js is a wonderful alternative if you desire simplicity and versatility in your front-end frameworks. Additionally, it is the lightest of all the frameworks.

It is a flexible open-source framework that may be used to construct web applications quickly and affordably. With it, small-scale static webpages or sophisticated traditional web apps with high traffic are both possible. Vue.js is considered among the best frameworks for SPA because it is;

  • Lightweight and easy to use
  • Virtual DOM results in faster dynamic HTML page rendering
  • MVVM software design architecture
  • User-friendly coding environment
  • Flexible to integrate with any third-party apps

3. Angular.js

Image source: pngegg.com

One of the popular open-source, JavaScript-based front-end frameworks for building single-page client-side apps is Angular.js. Microsoft, Google, and PayPal are some well-known Angular.js users and Google developed it. Angular.js can simultaneously load all the pages by delivering the entire website's content directly from the server to the browser. When a link is clicked, the page sections are immediately updated rather than requiring a page reload once they have loaded. Because AngularJS reduces server demand, pages can load faster. The two-way data binding functionality relieves the stress of developing several codes. Here, data integration between the model and display components happens automatically. Additionally, Angular.js utilizes an MVC design. Here are a few characteristics of this framework for single-page applications:

  • Dependency injection
  • High performance and speed
  • Highly extensible with other libraries
  • Two-way data binding feature eliminating the need for DOM manipulation
  • No dependencies to code

4. Ember.js

Image source: wikipedia.org

Ember.js is an open-source framework with strong opinions that allows for more flexibility. It employs a widget-based methodology known as Ember components and a two-way data binding pattern is used. With minimal scripting, the templates integrated with Handlebars are updated automatically as the data changes. EmberJS is widely used by Microsoft, Netflix, LinkedIn, Live, Vine, AppleMusic, and other platforms. Ember.js features a strong routing mechanism, and uses the Convention over Configuration (CoC) model and MVVM design pattern. EmberJS offers a really useful data library and many people favor it over competing frameworks because of its user-friendly API.

To encourage the finest developing methods, the framework provides defaults and simple templates. Additional features provided by Ember.js are:

  • It has all tools developers need to create a well-performing application and provides thousands of carefully vetted, high-quality npm packages
  • It is a scalable, easy-to-use UI architecture
  • Ember.js CLI comes built-in with an environment with rapid rebuilds and auto-reload
  • Easy testing and deployment of web applications

How to build a Single Page Application?

To create a high-quality single-page web application you need a team, the appropriate equipment, and time. Make sure the components are connected and work harmoniously.

1. Tools and technologies

  • JavaScript and its Frameworks: Development teams have access to various JS frameworks, including Angular.js and Vue.js, as well as pure JS and React.js development.
  • AJAX: AJAX is a technology required to launch a SPA and is for asynchronous JavaScript and XML. It facilitates data transfer between the client and server and is in charge of an "indiscernible" reload.
  • Back-end technologies: You are free to make your own decisions here. Some prefer using Node.js for developing the back-end of SPAs, but PHP and its frameworks will also function well. For instance, you might create an API-driven single-page app by combining the front-end React.js framework with the back-end Ruby on Rails framework.
  • Database: It may seem difficult to choose between a relational and non-relational database, but all you need to do is determine your goals and weigh the benefits and drawbacks of each type. An SQL database will be a better option if you operate with well-structured, generally constant data. It saves you storage space and keeps your information organized. However, be prepared for difficult database upgrades and upkeep if you need to manage multiple sorts of data. A NoSQL database, which keeps all available data as files, is an alternative. Although it is less structured, creating and maintaining such a database takes less time.

2. Team

Makes sure your development team is proficient in JavaScript before considering a single-page application architecture for your solution. The secret to establishing an effective app is having high proficiency in JS technology. You'll require the following in your team:

  • UI/UX designers to create a fantastic website.
  • JavaScript programmers to produce top-notch front-end code.
  • Backend engineers to ensure that the app's interface is seamlessly integrated with the server.
  • QA experts to properly test the application.

3. Time

Keep in mind that the time it takes to build a SPA entirely relies on your needs and expectations. The intricacy of the characteristics, the size of the team, the amount of time spent on research, and the decision-making process all impact the outcome.

Why use a SPA?

A single-page application is a program that runs in a browser and doesn't require the page to be reloaded while it is being used. You might use Facebook, Google Maps, Gmail, Twitter, Google Drive, or even GitHub as daily apps. These are all illustrations of SPAs.

The user experience (UX), which allows the user to experience the app in its native surroundings without waiting for page reloads or other interruptions, is one of the finest benefits of a properly set-up SPA. You stay on the same page, which uses the JavaScript computer language as its foundation.

Examples of Single-Page Applications

The most well-known SPA examples include Netflix, Facebook, and Gmail, which are all widely utilized globally. To create scalable experiences, businesses use SPAs created using frameworks like React.js and Angular.js.

1. Netflix

The popular entertainment streaming service uses the React framework to enable lag-free access to TV box sets and movies for its subscribers. It is safe to assume that Netflix's SPA approach fully uses this technique, given the volume of data being broadcast and the number of users using the service.

2. Facebook

One example of a single-page web app is Facebook's newsfeed. When you scroll through the previous videos or click on other buttons, specific bits of content is loaded on the page. You can go through the experience without leaving the page.

3. Gmail

The browser stays on the same webpage when you click on the messages in your inbox. The application will use the same URL for the first three web pages of the navigation and actively add new material as you navigate through.

What is a Progressive Web Application (PWA)?

A Progressive Web Application (PWA) is a type of web app that can operate both as a web page and mobile app on any device. It is a fantastic solution for your online store's low conversion rates and bad mobile UX. A PWA aims to give a native-like user experience with faster conversion and cleaner browsing -even with a slow Internet connection - by utilizing standard technologies.

PWAs are written with HTML, CSS, and JavaScript. They display and function exactly like standard web pages (which means they are searchable in internet browsers). However, they also offer capabilities that are exactly the same as those offered by mobile apps: they are quick, can operate offline, send push alerts, and utilize user devices.

The technology of PWA (Progressive Web App)

PWAs have many advantages, including allowing users to access standalone applications through webpages.

Three elements make up the core of a PWA:

  1. an application shell,
  2. service workers,
  3. a web app manifest.
Image source: pexels.com

PWA web apps use the following technologies:

1. Ionic

Ionic is a powerful PWA solution built on the cutting-edge tech stack of Apache Cordova and the Angular.js framework. It enables developers to leverage rival frameworks. For PWA functionality, Ionic offers a comprehensive toolset that includes UI components, unit testing, pre-built routing, etc..

2. Angular.js

As the third most popular PWA development technology and one of the first JS frameworks, Angular.js follows a clear-cut methodology. It has all the necessary tools, enabling programmers to quickly create a number of functionalities. Providing a process simplification to develop a PWA quickly. It has one of the largest user communities and is constantly synchronized with Google for updates.

3. React PWA Library

React.js framework is used to create single and multi-page apps. Developers may create server-side and client-side rendered pages, routing, and API integrations with the help of extra JS frameworks. React.js is one of the top choices for developing progressive web apps and is a great option for PWA development because it provides better documentation, extensive libraries, ecosystem support, a large developer community, etc.

What is a Web App manifest?

There is a [JSON] document called a Web App manifest that contains the startup parameters and default settings for a web application when it is launched. 

 An associated manifest URL, or the [URL] where the manifest was fetched, is a part of every manifest. Web application manifests consist of the following keys:

  • Background colors
  • Categories
  • Display
  • Icons
Image source: pexels.com

What is a service worker in PWA?

Specialized JavaScript components called "service workers" function as intermediaries between web browsers and web servers. By enabling offline access, they want to increase dependability and enhance page performance. Service workers are a crucial component of a PWA. They enable offline access, push notifications, and quick loading (regardless of the network).

Even when a user is offline, a service worker acts as a network proxy to intercept app requests for resources that fall within its purview. It can then choose whether to offer the resource using the Cache Storage API directly from the cache, from the network - as would typically occur in the absence of a service worker- or, by creating it locally using an algorithm. You may offer an experience that is comparable to what a platform app offers by doing this. Even completely off the grid, it can still work.

Image source: Author's library

How to build a Progressive Web Application (PWA)?

All of your users will receive the same core experience as rapidly as possible thanks to PWA's use of progressive enhancement. This loads the most crucial material first, before adding presentational and functional features as needed. PWA is the best option if you want to reach the largest audience possible. We'll go over how to make your app progressive in this section.

1. Serve over HTTPS

For PWA to use service workers and permit home screen installation, HTTPS is necessary. An SSL certificate is inexpensively available from your domain registrar, and it may be set up using your hosting provider. SSL adds an extra layer of security to the web, helping users feel secure in using your site.

2. Create an application shell

The first thing that loads and the first thing the user sees is your app shell. To ensure it loads as quickly as possible and your user doesn't have to spend more time staring at a blank screen than required, it should exist entirely in your index HTML document with inline CSS. The progressive enhancement pattern includes the application shell. As soon as possible, your app should provide the user with content, and as new data (usually JavaScript) loads, it should gradually improve that content.

{% code-block language="js" %}
<body> <div id="root">
<div id="container"> 
<div class="inner-container"> 
<div id="header"> 
<img src="/assets/icon.png" alt="logo" /> 
<div id="loading-container"> 
<img src="/assets/icon.png" alt="logo" id="loader"/> 
// index.js ReactDOM.render 
); {% code-block-end %}

3. Register a Service Worker

You will require a service worker to access the full range of PWA benefits (push alerts, caching, install prompts, etc.). Fortunately, they're relatively simple to set up. The first thing we do is see if the user's browser is compatible with service workers. If the answer is yes, the service worker file, called serviceworker.js, can then be registered. Keep in mind that at this point, the file can be left blank since nothing special is required inside of it.

{% code-block language="js" %} <script>
if ('serviceWorker' in navigator) { window.addEventListener('load', function()
{ navigator serviceWorker register('service-worker.js').then(fun //
Registration was successful console.log('Registered!'); }, function(err) { // registration failed :(
console.log('ServiceWorker registration failed: ', err); }).catch(function(err) { console.log(err);
}); });
} else { console.log('service worker is not supported');
</script> Il service-worker.js self.addEventListener('install', function() {
console.log('Install!'); }); self.addEventListener("activate", event => {
console.log('Activate!'); }); self.addEventListener('fetch', function(event) {
console.log('Fetch!', event.request); }); {% code-block-end %}

4. Add push notifications

Through the web Push API, service workers enable push notifications for your users. From within your service worker file, you can tap into self.registration.pushManager to gain access to it. We won't discuss this because sending push notifications strongly depends on your backend configuration. Google's Firebase service includes Firebase Cloud Messaging for comparatively simple push notifications if you're building an app from scratch. Remember: ensure you keep your design files safe in cloud storage. The code demonstrates using the Push API to sign up for push notifications.

{% code-block language="js" %}}
"short_name": "Chat",
"name": "Chat",
"icons": [
"sizes": "192x192",
"type": "image/png"
"start_url": "/?utm_source=homescreen",
"background_color": "#e05a47",
"theme_color": "#e05a47", "display": "standalone" {% code-block-end %}

5. Add a web app manifest

You must include a manifest.json in the application's root directory to make it installable. Consider this an application description, similar to what you may submit to the App Store. It has a name, a description, a splash screen, and icons. A sample of some of the features your manifest can include is shown in the code below.

{% code-block language="js" %}
"short_name": "Chat",
"name": "Chat",
"icons": [
"sizes": "192x192",
"type": "image/png"
"start_url": "/?utm_source=homescreen",
"background_color": "#e05a47",
"theme_color": "#e05a47", "display": "standalone"
{% code-block-end %}

6. Configure the install prompt

Chrome will automatically ask users to add a PWA to their home screen when they access one that has a service worker and manifest, provided the following conditions are met: two visits to the website are required, with a five-minute gap between each. Here, the goal is to wait until a user expresses interest in your application before requesting that they make it a permanent part of their device.

{% code-block language="js" %}
Window.addEventListener(‘beforeinstallpromt’, e = > {
Console.log(‘beforeinstallprompt Event fired’) ;
e.preventDefault ();
// Stash the event so it can be triggered later.
This.deferredPrompt = e;
Return false;
} ) ;
// When you want to trigger prompt”;
This.deferredPrompt.user.Choice.then(choice = > {
} ) ;
This.deferredPrompt = null; {% code-block-end %}

7.  Analyze your app's performance

Performance is the core of PWAs. Users should be able to access your software quickly regardless of the network. Although caching and offline functionality are very helpful, your application should still load quickly even if the user's browser does not support service worker technologies. Providing a fantastic experience for everyone, independent of device modernity or network conditions, is the concept of progressive enhancement.

What are the benefits of PWAs?

1. Availability in the offline mode

If the internet connection is spotty or nonexistent, websites won't correctly show their content. On the other hand, mobile apps are frequently self-contained and enable offline use. As a result, they promote engagement and provide increased availability. PWA also provides this.

2. Smooth installation

Users can download a PWA directly from a webpage to their device to install it. Similar to a mobile app, a PWA has its own icon on phones and tablets.

3. Use of hardware features

Push notifications are one of several smartphone functionalities that may be implemented using PWAs. Additionally, PWAs can benefit from hardware attributes of mobile devices like the camera or geolocation.

Examples of Progressive Web Applications (PWAs)

1. Uber

The Uber web app was completely redesigned as a PWA to provide an identical booking experience to the native mobile app.

2. BMW

High-resolution photographs and videos are the first things that anyone would notice, and the website loads almost rapidly with all of these features.

3. Flipboard 

One of the best PWAs for online news is Flipboard. The PWA uses as little data as possible to provide a smooth and quick browsing experience with a stunning layout.

4. Starbucks

Starbucks created a PWA of their online ordering system to give all of their customers easy access and a user-friendly online ordering experience that is comparable to their native app.

The key differences between SPA vs. PWA

Now, you might have some questions about these two options like; What are the key differences between progressive web apps and single-page applications? Why are they so appealing to corporations and developers? Do they have any flaws? What makes them different from one another?

Let's explore their key differences:

Image source: pexels.com

1. Caching

SPAs only support a few caching techniques, which developers can use depending on the needs of each project: DOM storage caching (either local or session-based, where all data is removed when the session has ended); or, when a large number of requests must be decreased, HTTP caching. HTTP caching preserves as much data as feasible on the client side.

In the case of PWA solutions, the caching can vary in the following way:

  1. Data caching in an autonomous performance mode;
  2. Reserved caching, when a website/app reacts to user requests based on its own dedicated cache without turning to the server.

2. Speed

Performance-wise, SPA- and PWA solutions are substantially faster than alternatives based on conventional architectures. However, PWAs offer an additional benefit in that they can operate independently and offline.

3. UX/UI

In comparison to standard web apps or sites, the user experience is significantly improved in both cases—SPAs and PWAs. Nevertheless, PWAs are slightly more well-thought-out in terms of UX than SPAs due to their capacity to load content quickly and their features.

4. Accessibility

Due to their offline interaction capabilities, PWAs are a step above other types of solutions from an accessibility perspective.

PWA VS SPA: Which is better?

To determine which is better for your website, it's critical to understand the differences between PWA and SPA. Comparing PWA vs SPA demonstrates that both are very effective choices for users and developers. The final decision is based on the needs, objectives, and abilities of your project. When designing your website, PWA is superior to SPA in many ways due to:

  • Loading Time:
  • Security
  • Accessibility
  • SEO
  • User interface

Which will be used in the future?

SPA and PWA apps are the future of web development, which will make the internet faster, more useful, and simpler to use. Design and development options seem limitless when these two are merged. For Android devices utilizing the Chrome browser, progressive web apps are currently a highly viable alternative to mobile apps. Cross-platform browser support for the underlying technologies is crucial if PWA apps are to serve as a credible alternative to app store apps. Although SPAs and PWAs are similar in some ways, more and more people are selecting PWAs over SPAs, given the advantages that PWAs offer.


As you can see from the comparison between PWA and SPA, both are excellent choices for users and developers. As noted, your decision should be based on your specific project needs, goals, and other factors, as well as on your abilities as the project owner or manager.

If you want to develop an authentic project based on PWA or SPA concepts, and gain the skills needed to excel as a remote software developer, apply to Microverse today!

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