Mention about continuous integration

README.md

@@ -38,6 +38,7 @@ If your company is exploring a modern JavaScript stack as well, you may find thi
   - [Types](#types---flow)
 - [Build System](#build-system---webpack)
 - [Package Management](#package-management---yarn)
+- [Continuous Integration](#continuous-integration)
 - [Hosting](#hosting---amazon-s3)
 
 Certain topics can be skipped if you have prior experience in them.
@@ -363,6 +364,28 @@ [email protected] was [released in May 2017](https://github.com/npm/npm/releases/tag/v5.
 
 - [Good old npm](https://github.com/npm/npm/releases/tag/v5.0.0)
 
+## Continuous Integration
+
+We use [Travis CI](travis-ci.com) for our continuous integration (CI) pipeline. Travis is a highly popular CI on Github and its [build matrix](https://docs.travis-ci.com/user/customizing-the-build#Build-Matrix) feature is useful for repositories which contain multiple projects like Grab's. We configured Travis to do the following:
+
+- Run linting for the project.
+- Run unit tests for the project.
+- If the tests pass:
+  - Test coverage generated by Jest is uploaded to [Codecov](https://codecov.io/).
+  - Generate a production bundle with webpack into a `build` directory.
+  - `tar` the `build` directory as `<hash>.tar` and upload it to an S3 bucket which stores all our tar builds.
+- Post a notification to Slack to inform about the Travis build result.
+
+#### Study Links
+
+- [Travis Homepage](https://travis-ci.com/)
+- [Codecov Homepage](https://codecov.io/)
+
+#### Alternatives
+
+- [Jenkins](https://jenkins.io/)
+- [CircleCI](https://circleci.com/)
+
 ## Hosting - Amazon S3
 
 Traditionally, web servers that receive a request for a webpage will render the contents on the server, and return a HTML page with dynamic content meant for the requester. This is known as server-side rendering. As mentioned earlier in the section on Single-page Apps, modern web applications do not involve server-side rendering, and it is sufficient to use a web server that serves static asset files. Nginx and Apache are possible options and not much configuration is required to get things up and runnning. The caveat is that the web server will have to be configured to route all requests to a single entry point and allow client-side routing to take over. The flow for front end routing goes like this: