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.
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 must be greater than a certain version, ~version means approximately equivalent (which means it can be up to the next minor version), and ^version means compatible (which usually means the highest version without a change in the major version). This means that given the same package...