npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! node-sass@4.14.1 postinstall: `node scripts/build.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the node-sass@4.14.1 postinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
分析一下，这个错误的出现是因为sass安装时获取源的问题，修改sass安装的源。
解决办法：使用taobao的npm
npm config set sass_binary_site=https://npm.taobao.org/mirrors/node-sass
回车后，再输入npm install就完美解决了。
npm install