Module build failed: Error: Cannot find module 'node-sass'

 在添加scss文件之后遇到该问题：

Module build failed: Error: Cannot find module 'node-sass'
    at Function.Module._resolveFilename (module.js:536:15)
    at Function.Module._load (module.js:466:25)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at Object. (E:\schoolNoc1.0.2\SchoolNoc\NOCSchool\node_modules\sass-loader\lib\loader.js:3:14)
    at Module._compile (module.js:635:30)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at loadLoader (E:\schoolNoc1.0.2\SchoolNoc\NOCSchool\node_modules\loader-runner\lib\loadLoader.js:13:17)
    at iteratePitchingLoaders (E:\schoolNoc1.0.2\SchoolNoc\NOCSchool\node_modules\loader-runner\lib\LoaderRunner.js:169:2)
    at iteratePitchingLoaders (E:\schoolNoc1.0.2\SchoolNoc\NOCSchool\node_modules\loader-runner\lib\LoaderRunner.js:165:10)

解决：

在项目目录下打开命令窗口，安装确实的文件（其他缺少的文件安装方法也类似如此）

npm install node-sass