[Yarn] Install Yarn2

This lesson goes over how to install yarn 2 through npm.

To install yarn 2 globally, we use

npm install -g yarn@berry

Init a project:

yarn init -y

To install yarn 2 to a specific project, we use 

yarn policies set-version berry

This creates a .yarnrc file and a .yarn/ directory. .yarnrc that sets the path to our yarn instance in the created .yarn/ directory that holds our new yarn version.

[Yarn] Install Yarn2

原文：https://www.cnblogs.com/Answer1215/p/12237021.html