This post is about my learning on performance techniques used to make Uber mobile web using React as fast as possible.
**Motivation**It’s been a year since Flipkart Lite was launched and few months since Housing Go was launched and I was always fascinated with the idea of how mobile web is a future and I wanted to give a try.
First I needed an app on which I can implement the perf techniques, and Uber had just recently launched their app with new design and it looked promising so I decided to clone the app using React.
It took me some time to build the basic implementation of the app, I have used https://github.com/uber/react-map-gl for the map and used svg-overlay to create a path from the source and destination along with the html-overlay.
Below is the gif of the app with basic interaction.
Now that I had the basic app to work on, I started to improve the performance of it.
I have used Chrome Lighthouse to check the performance of the web app in each stage.
initially load time looked like this.
To improve the above stats I have used following techniques
**_Code Splitting — reduces load time from 19sec to 4sec_**First thing I did was used webpack code splitting techniques to divide the app into various chunks based on the route and load what is needed for that particular route.
This I did by using the getComponent api of react-router where I require the component only when the route is requested.
I also extracted the vendor code using CommonChunkPlugin in webpack.
With this I have reduced the load time from 19secs to 4secs.
Performance metrics using code splitting
**_2. Server side rendering — reduces load time from 4sec to 921ms_**I then implemented SSR by rendering the initial route on the server and passing on to the client.
I used Express for this on the backend and used match api of the react-router
Thanks to SSR, now the load time is 921ms.
Performance metrics using SSR
3. Compressed static assets — **_reduces load time from 921ms to 546ms_**Then I decided to compress all the static files, this I did this by using CompressionPlugin in the webpack
and express-static-gzip to serve the compressed file from the server which falls back to uncompressed if required file is not found.
yippee I saved almost 400ms. Good job, Narendra!
Performance metrics after compressing the assets
**_4. Caching — helped load time of repeat visits from ~500ms to ~300ms_**Now that i had improved the performance of my web app from 19seconds to 546ms, I wanted to cache static assets so the repeat visits are much faster.
I did this by using sw-toolbox for browsers which support service workers
and cache-control headers for browsers which don’t support.
By doing this I improved the repeat visit by approximately 200ms.
Repeat visit without service worker
Repeat visit with service worker
**5. Preload and then load**I have used <link rel="preload" ... as="script"> in the head tag and used prefetch for the browser which doesn’t support preload.At the end of the body I load the application JS in a regular <script>tag.For more about preload and prefetch please visit https://css-tricks.com/prefetching-preloading-prebrowsing/
Finally tested with Google PageSpeed and this is the result
Scores from PageSpeed Insights
This has been a good learning for me, I know I can optimize more and will keep exploring. Performance improvement is an ongoing process this is just a benchmark to what I have achieved. Give a try with your app and let me know your story.
Github: https://github.com/narendrashetty/uber-mobile-webLive Demo: https://uberweb.herokuapp.com/ or https://uberweb-v2.herokuapp.com/
Please give a visit to the demo on your mobile browser and share your inputs with me. (Since I hosted it on heroku, it’s goes down when it has no visits. Don’t lose patience if it doesn’t load at first :P Such an irony).
Maintaining Performance is like a chess, one wrong move and it undos lot of hardwork done.
Thanks for reading, If you liked this article, click “Recommend” or write a response below. You can connect with me on Twitter @narendra_shetty.