Yarn的安装与使用详细介绍

Yarn is a package manager for your code. It allows you to use and share code with other developers from around the world. Yarn does this quickly, securely, and reliably so you don't ever have to worry.关键意思就是，快速,安全,可靠。你下载的包将不再重新下载。而且确保在不同系统中可以正常工作。