I’m excited about the future PWAs offer. The web, including mobile apps, should be open. It should be competitive. Despi

In this article, we attempt to explain the rationale behind our choice of React-Native, briefly describe the onboarding challenges, and provide insights on some techno-functional aspects. Besides, the article briefly touches upon how Flipkart is currently using React-Native for its application development.,Every change in the app is profiled to analyse its impact on the core metrics. In our initial experiments with React-Native Android apps, the page load metrics were not as good as Native.,Flipkart, the largest e-commerce player in India, has over 100 million app downloads and 400 million visits every week. The React-Native journey of these applications started back in 2016.,Reusing the React Instance Managers: We were building them again while switching between stacks. Rebuilding these managers requires a re-parse of JS, leading to slowdowns. You need to create and then cache in memory.,Much to my own disappointment, I recently made the switch to AirPods, a device I’d avoided for as long as possible in some minor act of rebellion against Apple’s ever-growing ecosystem of proprietary gadgets. To me, AirPods symbolize the kind of needless iteration and waste that’s become synonymous with Apple’s brand. (Not only did the company force customers to adopt AirPods through a series of blunted design changes, but the product itself has also been engineered so as to persist on Earth long after we, the human consumer, are dead and gone.),I’m excited about the future PWAs offer. The web, including mobile apps, should be open. It should be competitive. Despite Facebooks and Googles and Apples, the web can remain open, and PWAs will play a role.,Increased development effort: At Flipkart, the features and designs are uniform by choice, so they behaved the same way across platforms. We built the features/pages on the web stack only once. However, because of stack differences in mobile app development, we had to build every feature separately for Android, iOS. This translated into a significant loss of productivity in the Engineering teams.,We built internal infrastructure to diff JS and enable clients to download patches. We could drop our payloads size by over 90% for our weekly releases. This has become much better today and we’ve moved from ‘module-level diffs’ to ‘binary diffing’ using ‘bsdiff’.,This revision in the thought process and discussion around deciding targets helped the entire team focus on the correct success metrics. After a few iterations, we could achieve the targets and React-Native became an obvious choice.,Delayed experiments and bug fixes: The adoption time for newer app versions was very high, especially Android. It was necessary to wait for significant adoption to run AB experiments and roll out critical bug fixes. Such delays can cause negative impact on sales numbers and the customer experience in large-scale sale scenarios such as Flipkart’s most popular sale event, ‘The Big Billion Days’.,A lot of teams get into conflicts between Native vs React-Native performance without setting targets. Our intent was to set targets and then see if React-Native can match it. The goal that we agreed internally was to go with React-Native, if we can maintain or do better than existing load time metrics and scroll FPS.,We read the source code and the comments on it, fixed memory leaks, and experimented with the possibilities in the usage of React-Native. Eventually, we saw success in migrating one of the most complex pages with no performance degradation.,When we started, the efficiency in delivering JS updates OTA and improving the performance of the infinite list were our primary concerns. We needed some kind of bundle diffing to push frequent updates.,To solve the infinite list problem, we had to build our own list view, which recycles cells instead of destroying and recreating to save memory and performance. Our first version was backed by native RecyclerView and UICollectionView, and in later revisions we built recyclerlistview in JS (only).,It’s true that optimised native apps can outperform React-Native versions most times. However, considering the benefits such as OTA updates, we came up with the success metric for this experiment.