命令为npm install --save file-saver并返回：
npm WARN The package enzyme is included as both a dev and production dependency.
npm WARN The package gulp-util is included as both a dev and production dependency.
npm WARN The package react-addons-test-utils is included as both a dev and production dependency.
+file-saver@1.3.3
added 1 package and removed 15 packages in 6.536s
我知道删除的其中两个包是react-google-recaptcha和react-async-script。另外，我没有使用npm的公共注册表。