Error - [sass] Error: Missing binding
C:\Users\chuanbiao.liu\helloworld-webpart\node_modules\node-sass\vendor\win32-x64-57\binding.node
Node Sass could not find a binding for your current environment: Windows
64-bit with Node.js 8.x


Found bindings for the following environments:
  - Windows 64-bit with Node.js 8.x


This usually happens because your environment has changed since running `npm
install`.
Run `npm rebuild node-sass --force` to build the binding for your current
environment.
[16:48:42] Error - 'sass' sub task errored after 1.53 s
 Missing binding
C:\Users\chuanbiao.liu\helloworld-webpart\node_modules\node-sass\vendor\win32-x64-57\binding.node
Node Sass could not find a binding for your current environment: Windows
64-bit with Node.js 8.x


Found bindings for the following environments:
  - Windows 64-bit with Node.js 8.x


This usually happens because your environment has changed since running `npm
install`.

Run `npm rebuild node-sass --force` to build the binding for your current
environment.










话不多说,执行  npm rebuild node-sass  命令,就可以了。还是不行的话先执行npm install node-sass,再执行一次!