方式一：
通过 cnpm 安装node-sass
cnpm install node-sass --save
方式二：
通过npm 安装
1、安装sass-loader
npm install sass-loader --save-dev
2、安装 node-sass
npm install node-sass --save-dev
如若不安装node-sass ，会出现如下错误：
ERROR Failed to compile with 1 errors 3:13:52 PM
error in ./src/styles/index.scss
Module build failed (from ./node_modules/sass-loader/dist/cjs.js):
Error: Cannot find module 'node-sass'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
at Function.Module._load (internal/modules/cjs/loader.js:562:25)
at Module.require (internal/modules/cjs/loader.js:692:17)
at require (internal/modules/cjs/helpers.js:25:18)
at getDefaultSassImplementation (D:WebStormProject ourism-supervision-service-platform
ode_modulessass-loaderdistgetDefaultSassImplementation.js:24:10)
at getSassImplementation (D:WebStormProject ourism-supervision-service-platform
ode_modulessass-loaderdistgetSassImplementation.js:19:72)
at Object.loader (D:WebStormProject ourism-supervision-service-platform
ode_modulessass-loaderdistindex.js:40:61)
@ ./src/styles/index.scss 4:14-225 14:3-18:5 15:22-233
@ ./src/main.js
@ multi (webpack)-dev-server/client?http://localhost:9999/sockjs-node (webpack)/hot/dev-server.js ./src/main.js