Add caching to improve the loading speed

[lunayach]

Enabled Caching to improve the loading speed.

Changes proposed in this pull request:

• Enabled service workers feature and added its configuration file.

• Link to live demo: http://pr-XXX-evalai.surge.sh

• The offline option was selected in the Network menu of chrome dev tools for simulating a real-life network situation. After reloading it again, keeping the "Offline" checked, it was still able to load the page quickly because it had cached all the static assets during the previous loading instance.
  

[Shekharrajak]

Thanks for your PR for improving the application loading.
There are few other good concepts that can be used :

• Lazy loading
• Compressing the images
• Updating the latest packages to latest version
• Build optimization flags, production flags in build command

What do you think ?

[Shekharrajak]

It is a good idea to add static images and files in cache memory. But isn't service worker works with https-server ?

We will love to see it working once we get the surge deployed URL. :)

[lunayach]

@Shekharrajak I'm glad you asked this. There is a ngsw.json which manages app's versions. Whenever a developer changes files locally, this file's version changes. Whenever, a user on the client side reloads his page, first only the request for ngsw.json would be made. If only it's found same, no other requests for files shall be made, else requests for new (or updated) files are made. Hence, an improved loading speed.

Yes, this would work by serving the production build using http-server.

[Shekharrajak]

Yes, this would work by serving the production build using http-server.

So how did you tested it? I am curious to see the loading speed difference and check this out in http://pr-101-evalai.surge.sh/

Can you test it by changing some content and serve it again ? Offline it would be showing old content and after running the server again and after refreshing the page it should be able to update the changed content.

[codecov-io]

Codecov Report

Merging #101 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #101   +/-   ##
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  Coverage   53.43%   53.43%           
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  Files          55       55           
  Lines        2358     2358           
  Branches      253      253           
=======================================
  Hits         1260     1260           
  Misses       1023     1023           
  Partials       75       75

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[RishabhJain2018]

Let's keep it on hold for now. We need to revisit this later for sure before launching v1.