npm install express报错解决：
npm ERR! code UNABLE_TO_VERIFY_LEAF_SIGNATURE
npm ERR! errno UNABLE_TO_VERIFY_LEAF_SIGNATURE
npm ERR! request to https://registry.npmjs.org/express failed, reason: unable to verify the first certificate
npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\Administrator\AppData\Roaming\npm-cache\_logs\2018-08-11T11_18_50_440Z-debug.log
解决方案：
在您的命令行运行：
npm config set strict-ssl false
重复做如下操作即可安装：
npm install express
