今天npm提示可以更新：
╭─────────────────────────────────────╮
│ │
│ Update available 5.6.0 → 5.7.1 │
│ Run npm i -g npm to update │
│ │
╰─────────────────────────────────────╯执行了一下，发现报错
➜ ~ ✗ npm i -g npm
npm ERR! Unexpected end of JSON input while parsing near '...ist":{"shasum":"b779a'
npm ERR! A complete log of this run can be found in:
npm ERR! /Users/user/.npm/_logs/2018-03-15T05_56_22_902Z-debug.log于是清理了一下cache，再执行，成功
➜ ～ ✗ npm cache clean --force
npm WARN using --force I sure hope you know what you are doing.
➜ ～ ✗ sudo npm i -g npm
/usr/local/bin/npm -> /usr/local/lib/node_modules/npm/bin/npm-cli.js
/usr/local/bin/npx -> /usr/local/lib/node_modules/npm/bin/npx-cli.js
+ [email protected]
added 63 packages, removed 6 packages and updated 49 packages in 17.184s