我在Windows 10上安装了nodejs v12.16.2以便与react-native一起学习东西，因此无需安装android studio或xocde。正如我在react-native文档中所读到的那样，最简单的方法是使用expo-cli，我使用以下命令将其安装到我的机器上，但是它不起作用：
$ npm install -g expo-cli
$ npm install expo-cli --global
$ yarn add global expo-cli
所有这些命令最终都会出现错误，我错过了什么以及如何解决此问题。 这是问题的详细信息：
npm install expo-cli --global npm WARN deprecated joi@14.0.4: This version has been deprecated in accordance with the hapi support policy (hapi.im/support). Please upgrade to the latest version to get the best features, bug fixes, and security patches. If you are unable to upgrade at this time, paid support is available for older versions (hapi.im/commercial).
npm WARN deprecated request@2.88.2: request has been deprecated, see https://github.com/request/request/issues/3142
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/traveling-fastlane-darwin@1.13.1 (node_modules\expo-cli\node_modules\@expo\traveling-fastlane-darwin):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/traveling-fastlane-darwin@1.13.1: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-freebsd-x64@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-freebsd-x64):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-freebsd-x64@2.2.8: wanted {"os":"freebsd","arch":"x64"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-darwin-ia32@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-darwin-ia32):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-darwin-ia32@2.2.8: wanted {"os":"darwin","arch":"ia32"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-darwin-x64@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-darwin-x64):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-darwin-x64@2.2.8: wanted {"os":"darwin","arch":"x64"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-freebsd-ia32@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-freebsd-ia32):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-freebsd-ia32@2.2.8: wanted {"os":"freebsd","arch":"ia32"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-linux-arm64@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-linux-arm64):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-linux-arm64@2.2.8: wanted {"os":"linux","arch":"arm64"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-linux-ia32@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-linux-ia32):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-linux-ia32@2.2.8: wanted {"os":"linux","arch":"ia32"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-linux-arm@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-linux-arm):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-linux-arm@2.2.8: wanted {"os":"linux","arch":"arm"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-sunos-x64@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-sunos-x64):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-sunos-x64@2.2.8: wanted {"os":"sunos","arch":"x64"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-linux-x64@2.2.8 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-linux-x64):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-linux-x64@2.2.8: wanted {"os":"linux","arch":"x64"} (current: {"os":"win32","arch":"ia32"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: @expo/ngrok-bin-win32-x64@2.2.8-beta.1 (node_modules\expo-cli\node_modules\@expo\ngrok-bin\node_modules\@expo\ngrok-bin-win32-x64):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for @expo/ngrok-bin-win32-x64@2.2.8-beta.1: wanted {"os":"win32","arch":"x64"} (current: {"os":"win32","arch":"ia32"})
npm ERR! Unexpected end of JSON input while parsing near '...in-proposal-unicode-p'
答案 0 :(得分：0)
由于npm中使用optionalDependencies安装了适用于您的平台的ngrok软件包，因此不可避免地会看到警告。因此，请不必为此担心。与您相关的错误是“ npm ERR！在...附近解析时，JSON输入意外结束”-有关此主题的文章很多，他们通常建议您执行以下操作：
npm cache clean --force npm i -g expo-cli 有关使用不同软件包的类似问题的示例，请参见https://stackoverflow.com/a/47896884/659988。