What is Isomorphic JavaScript and What Can it Help With?

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What is Isomorphic JavaScript and What Can it Help With?

When a user opens their favorite webpage or application, there is a great deal of things that happen in the background. The browser and server go to work sending requests, parsing and rendering to provide a webpage to the user within seconds. Some developers choose to render their webpages server side while others opt for client side rendering. Previously when users interacted with the webpage, the server was in charge of rendering each page in response to user interaction. With the rise of Single Page Applications (SPA) much of the webpage rendering responsibility was handed over to the client or user’s browser. While this had many advantages it also had several disadvantages. Client side and server side rendering each has its benefits but what if there was a way to obtain the best of both worlds? Isomorphic JavaScript aims to do just that.

Isomorphic JavaScript

Isomorphic JavaScript allows you to write and execute the same code in the client and server. The benefits of this overlap are numerous. The client and server can now collaborate in a way that wasn’t possible before and therefore address and improve upon some of the shortcomings each side previously had. For example, while SPAs do many things, they have two crucial drawbacks, namely reduced speed and SEO compatibility. The initial SPA page can be slow to load because of the time it takes to load and parse client side JavaScript. While this delay is only a matter of a few seconds or milliseconds, users can become impatient and leave the site causing a company to lose revenue. Also, since SEO crawlers parse HTML on the server, they are unable to index SPAs. Isomorphic JavaScript eliminates these problems.

Another benefit is that there is less code to write for the developers and code redundancy can be avoided as the client and server can now share code. Development times are reduced and testing is more efficient because developers no longer have to code the same functionality in two different programming languages for the client and server.

Isomorphic JavaScript Libraries and Frameworks

There are many isomorphic JavaScript libraries and frameworks available to ease and assist web development. Below is a list of reputable frameworks and libraries.   

MeteorMeteor is one of the most popular and thorough full-stack isomorphic JavaScript frameworks. It is open source, works across many platforms and is known for high performance. Meteor provides technologies for every layer of the stack but also allows the flexibility of replacing those technologies with existing ones that the developer favors. Optimistic UI updating is a central feature of Meteor.

ReactReact is a library created by Facebook that focuses on UI development. React uses the concept of virtual DOM to improve performance as well as provide isomorphic capabilities. Also, it is easy to create isomorphic Express apps with React.

Rendr– This is a library created by Airbnb which runs Backbone.js on both the client and server. Rendr aims to retain the feel of a client side Backbone app while providing the benefits of server side rendering. While Rendr is no-where nearly as comprehensive as full stack frameworks, it allows developers to easily modify and build upon the library.

Derby– This is another full-stack isomorphic framework. Derby makes it easy to sync data across clients and servers and is great for real time collaboration. Derby utilizes and builds upon Node.js modules and ShareJS to provide it’s core functionalities.


Isomorphic JavaScript allows the client and server to execute the same code. This results in reduced development times, increased efficiency, faster page rendering, SEO compatibility and more. Web development and JavaScript are constantly evolving entities that have come a long way from when they first started. Isomorphic JavaScript is predicted to be the next big step in the evolution of web development.