One CLI for webpack must be installed. These are recommended choices, delivered as separate packages:

C:Usersarn>webpack -v
One CLI for webpack must be installed. These are recommended choices, delivered as separate packages:
 - webpack-cli (https://github.com/webpack/webpack-cli)
   The original webpack full-featured CLI.
We will use "npm" to install the CLI via "npm install -D".
Do you want to install 'webpack-cli' (yes/no):
You need to install 'webpack-cli' to use webpack via CLI.
You can also install the CLI manually.

安装webpack的时候 遇到的情况; 直接按照提示安装 提示Module webpack-cli 不存在

解决方案

npm install  webpack-cli -g