ubuntu 18.10 安装 node12.6

# ubuntu 18.10 安装 node12.6
1. tar node-12.tar.xz  --directory /usr/bin
2. node -v ; npm -v; npx -v
3.react.js 安装步骤
    1. 修改npm 安装源，加速下载 npm config set registry https://registry.npm.taobao.org
    2. npx install -g create-react-app
    4. 创建项目 create-react-app test-react
    5. 启动项目
       cd test-react
       npm start

4. React 官方中的一句话：
    It’s fine to copy and paste code 
    as you’re following along the tutorial, 
    but we recommend to type it by hand. 
    This will help you develop a muscle memory 
    and a stronger understanding.