安装了nodejs5.0,在windows命令行运行npm update，提示：
下安装npm提示：
$ npm update
npm WARN install Couldn't install optional dependency: Unsupported
这咋弄？
转自http://stackoverflow.com/questions/34469823/npm-warn-install-couldnt-install-optional-dependency-unsupported
The warning message is just a warning message and not an error. It does not affect the application.
It is a log message that an optional dependency could not be installed because it is not supported/needed on your current platform/cpu-arch. For example the package fsevents is often used as optional dependency but fails on any system that is not a Mac.
To show what package is throwing this message, run
$ npm install --verbose
This warning could also be triggered by packages having an engine set to something lower than what you are running. You can try
$ pm_config_engine_strict=false npm install
to get around this