Using yarn instead of npm

npm is the default package manager, but Facebook, in collaboration with Exponent, Google, and Tilde, has since developed a better alternative, called yarn, which we will use instead.

yarn (https://yarnpkg.com/en/) uses the same https://www.npmjs.com/ registry as the npm CLI. Since they both just install packages inside node_modules directories and write to package.json, you can use npm and yarn interchangeably. The differences are in their methods for resolving and downloading dependencies.

Package version locking

When we specify our dependencies inside our package.json file, we can use symbols to indicate a range of acceptable versions. For example, >version means the installed version...