Note that the development build is not optimized. To create a production build, run npm run build. node:events:504 throw er; // Unhandled 'error' event ^ Error: spawn cmd ENOENT at Process.ChildProcess._handle.onexit (node:internal/child_process:283:19) at onErrorNT (node:internal/child_process:478:16) at processTicksAndRejections (node:internal/process/task_queues:83:21) Emitted 'error' event on ChildProcess instance at: at Process.ChildProcess._handle.onexit (node:internal/child_process:289:12) at onErrorNT (node:internal/child_process:478:16) at processTicksAndRejections (node:internal/process/task_queues:83:21) { errno: -4058, code: 'ENOENT', syscall: 'spawn cmd', path: 'cmd', spawnargs: [ '/c', 'start', '""', '/b', 'http://localhost:80/' ] }

这个错误信息表明在运行开发构建时出现了问题。它提示你需要运行 `npm run build` 命令来创建生产构建。此外，在 Windows 平台上，可能需要安装一些额外的依赖项才能成功运行。你可以查看以下链接，了解如何解决这个问题：

- https://stackoverflow.com/questions/37420139/error-spawn-enoent-on-windows
- https://github.com/facebook/create-react-app/issues/1083

相关问题

Note that the development build is not optimized. To create a production build, run npm run build.

根据提供的引用内容，"Note that the development build is not optimized. To create a production build, run npm run build." 是一个提示，意思是开发版本的构建不是经过优化的，要创建一个生产版本的构建，需要运行命令 "npm run build"。这个提示可能是在使用React、Redux和Saga等技术栈时出现的。

以下是一个演示如何创建生产版本的构建的例子[^1]：

npm run build

这个命令会执行构建脚本，将开发版本的代码进行优化和打包，生成一个生产版本的构建文件。

Note that the development build is not optimized. To create a production build, run npm run build.

As an AI language model, I do not have the ability to run npm run build or any other command-line interface tools. However, I can provide you with information about the statement you mentioned.

The statement "Note that the development build is not optimized. To create a production build, run npm run build" is a common message that developers encounter when working with the Node.js package manager (npm) and building applications using frameworks such as React or Angular.

In essence, the statement is a reminder that the development build of your application is not optimized for performance and should not be used in a production environment. Instead, developers are advised to run the "npm run build" command to create a production build of their application, which is optimized for performance and can be deployed to a production server.

In summary, if you want to optimize your application for production use, you should run the "npm run build" command.