Use libraries dedicated to mobile and build features faster on many platforms at once, without compromising on the performance and user experience.

An Introduction

The following article is a part of The Ultimate Guide to React Native Optimization and describes the fourth point of this guide: the importance of using dedicated libraries for mobile.

Why is it important?

React Native gives you total control and freedom in choosing the way you build your apps. It allows you to write the code in JavaScript, reuse your current React components and use various libraries. But what you need to remember is that not every library is optimized for mobile. Using non-optimized libraries may cause some serious performance and user experience issues that can negatively impact the business side of your project. In this article, we will tell you how to avoid such problems and choose the right libraries for your apps

In the previous parts of our guide, we have discussed:

Be sure to check them out.

Now, let’s dive into the best practices for choosing the libraries dedicated to mobile.

Always remember to use libraries dedicated to the mobile platform

Issue: You use web libraries that are not optimized for mobile

As discussed earlier, one of the best things about React Native is that you can write the mobile application with JavaScript, reusing some of your React components and doing the business logic with your favorite state management library.

While React Native provides web-like functionality for compatibility with the web, it is important to understand that it is not the same environment. It has its own set of best practices, quick wins, and constraints.

For example, while working on a web application, we don’t have to worry too much about the overall CPU resources needed by our application. After all, most of the websites run on devices that are either plugged to the network or have large batteries.

It is not hard to imagine that mobile is different. There’s a wide range of different devices with different architectures and resources available. Most of the time, they run on battery and the drain caused by the application can be a deciding factor for many developers.

an illustration that symbolizes battery drain and user being not happy about it

In other words – how do you optimize the battery consumption both in the foreground and background can make all the difference.

Not optimized libraries cause battery drain and slow down the app. The OS may limit your application capabilities.

While React Native makes it possible to run the same JavaScript on mobile as in the browser, that doesn’t mean you should be doing this every time. As with every rule, there are exceptions.

If the library depends heavily on networking, such as real-time messaging or offers an ability to render advanced graphics (3D structures, diagrams), it is very likely that you’re better going with the dedicated mobile library.

The reason is simple – these libraries were developed within the web environment in the first place, assuming capabilities and constraints of the browser. It is very likely that the result of using a web version of a popular SDK will result in extraneous CPU and memory consumption.

Certain OSes, such as iOS, are known to be constantly analyzing the resources consumed by the application in order to optimize the battery life. If your application is registered to perform background activities and these activities take too much of the resources, the interval for your application may get adjusted, lowering the frequency of the background updates that you initially signed up for.

Solution: Use a dedicated, platform-specific version of the library

Let’s take Firebase as an example. Firebase is a mobile platform from Google that lets you build your apps faster. It is a collection of tools and libraries that enable certain features instantly within your app.

Firebase contains SDKs for the web and mobile – iOS and Android respectively. Each SDK contains support for Realtime Database.

Firebase and ios, android and javascript

Thanks to React Native, you can run the web version of it without major problems:

An example reading from Firebase Realtime Database in RN

However, this is not what you should be doing. While the above example works without issues, it does not offer the same performance as the mobile equivalent. The SDK itself also contains fewer features – no surprises here – web is different and there’s no reason Firebase.js should provide support for mobile features.

In this particular example, it is better to use a dedicated Firebase library that provides a thin layer on top of dedicated native SDKs and offers the same performance and stability as any other native application out there.

React Native Firebase

Here’s how the above example would look like:

An example reading from Firebase Realtime Database in RN

As you can see, the difference is minimal and boils down to a different import statement. In this case, the library authors did a great job mimicking the API to reduce the potential confusion while switching back and forth between the web and mobile context.

Benefits: Provide the fastest and most performant support with no harm to the battery life

React Native is all about giving you control and freedom to choose how you want to build your application.

For simple things and maximum reusability, you can choose to go with the web version of the library. That will give you access to the same features as in the browser at relatively low effort.

For advanced use cases, you can easily extend React Native with a native functionality and talk directly to the mobile SDKs. Such escape hatch is what makes React Native extremely versatile and enterprise-ready.

It enables you to build features faster on many platforms at once, without compromising on the performance and user experience – something other hybrid frameworks made a standard tradeoff.

Summary

Libraries can make the development process easier and faster but it’s crucial to choose the right ones. Using libraries that are not optimized for our target device (mobile in this case) can seriously harm the performance and user experience of your apps. It may lead to undesirable business consequences such as a decrease in the conversion rate of your products.

In the next part of our guide, we will describe how to find the balance between native and JavaScript.

Callstack

We are the official Facebook partners on React Native. We’ve been working on React Native projects for over 5 years, delivering high-quality solutions for our clients and contributing greatly to the React Native ecosystem. Our Open Source projects help thousands of developers to cope with their challenges and make their work easier every day.

Contact us if you need help with cross-platform or React Native development. We will be happy to provide a free consultation.