怎么把Npm和NodeJS更新到最新版本？

See the docs for the update command:

npm update [ [ ...]]

This command will update all the packages listed to the latest version (specified by the tag config). It will also install missing packages.

Additionally, see the FAQ:

How do I update npm?

npm install -g npm

Please note that this command will remove your current version of npm. Make sure to use sudo npm install -g npm if on a Mac.

You can also update all outdated local packages by doing npm update without any arguments, or global packages by doing npm update -g.

Occasionally, the version of npm will progress such that the current version cannot be properly installed with the version that you have installed already. (Consider, if there is ever a bug in the update command.) In those cases, you can do this:

curl https://www.npmjs.com/install.sh | sh

To update Node.js itself, I recommend you use nvm, the Node Version Manager.