How I built a super fast Uber clone for mobile web

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@narendrashettyNarendra N Shetty

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-web
Live 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.

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