create-react-app通过设置代理，可以在公司防火墙后面使用任何方法。

我已经在npm和yarn上设置了代理，但这是我在尝试执行create-react-app my-app以下操作时看到的内容：

Creating a new React app in F:\react\my-app.

Installing packages. This might take a couple of minutes.
Installing react, react-dom, and react-scripts...

You appear to be offline.
Falling back to the local Yarn cache.

yarn add v0.23.4
info No lockfile found.
[1/4] Resolving packages...
error Couldn't find any versions for "react" that matches "latest" in our cache. Possible versions: ""
info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.

Aborting installation.
  yarnpkg add --exact --offline react react-dom react-scripts has failed.

Deleting generated file... package.json
Deleting my-app / from F:\react
Done.