Let's briefly talk about node.js version control nvm and n_node.js

Today’s topic includes 2 parts

1. Use nvm or n for version control under node.js
2. After nvm installs the node.js version, restart the terminal node, and the npm environment variable becomes invalid

Part 1: What to use to manage node.js version

First of all, we should cheer and celebrate that node.js has finally released the historic official version 1.0. Although what we see is V4.0, it is actually the true meaning of node.js 1.0. io.js has lived up to expectations and is completed. Its mission.

Looking back at the development speed of node.js and io.js in the past few years, and the iterative release of various versions, it is necessary for us to use a node.js version management tool to control the node.js version of the current system.

Why do you do this?

The latest V8 engine has been used in the new version. All the new features of ES 6 can be used. Can you bear it?
However, if you upgrade recklessly, the first problem is that your development environment and online release environment may be different, so the consequences will not be much. If something goes wrong, just wait for the boss to come and kill you.
The second problem may be that some previous open source packages need to be recompiled, especially those written in c modules.

So, you need a node.js version management software

What are the popular node.js version managements now?

nvm

We use brew to install nvm

brew install nvm

Note here
After brew is installed, be sure to set it in your bash or zsh configuration file, otherwise when you restart the terminal, you will find that the node and npm environment variables are invalid

Here we want to intersperse the second topic we want to share
Solution to terminal node and npm failure after nvm restarts

If you use the brew installation method above
When the installation is successful, please follow the steps below to set up your shell configuration file

brew info nvm

You will see the following output help message

nvm: stable 0.26.1 (bottled), HEAD
Manage multiple Node.js versions
https://github.com/creationix/nvm
/usr/local/Cellar/nvm/0.26.1 (3173 files, 56M) *
 Poured from bottle
From: https://github.com/Homebrew/homebrew/blob/master/Library/Formula/nvm.rb
==> Caveats
Add NVM's working directory to your $HOME path (if it doesn't exist):

 mkdir ~/.nvm

Copy nvm-exec to NVM's working directory

 cp $(brew --prefix nvm)/nvm-exec ~/.nvm/

Add the following to $HOME/.bashrc, $HOME/.zshrc, or your shell's
equivalent configuration file:

 export NVM_DIR=~/.nvm
 source $(brew --prefix nvm)/nvm.sh

Type `nvm help` for further information.

Bash completion has been installed to:
 /usr/local/etc/bash_completion.d

We need to follow the method provided above and first create a .nvm file in the user update directory

mkdir ~/.nvm

Then copy the nvm-exec file to the .nvm directory you just created

cp $(brew --prefix nvm)/nvm-exec ~/.nvm/

Then edit your bash configuration file $HOME/.bashrc. If you use zsh then edit the $HOME/.zshrc configuration file

nano ~/.bashrc

or

nano ~/.zshrc

Paste the following content into it

export NVM_DIR=~/.nvm
source $(brew --prefix nvm)/nvm.sh

Finally make your shell configuration take effect in time

source ~/.bashrc

or

`source ~/.zshrc'

Finally, you will no longer have the problem of closing the terminal and restarting, or restarting the machine to find that node, npm and other system environment variables are invalid.

The difference between nvm and n

nvm is similar to Python’s virtualenv or Ruby’s rvm. It is an independently installed software
n is actually an npm global open source package, which needs to be installed globally using npm
n is lighter, but nvm is more independent.

If you have a new computer and you want to use version management, then nvm is your choice because it is an independent software. After installation, you can download and switch the version you need at will.

But n is a package that depends on npm, which means that if your computer environment does not have node / npm, you cannot use n yet.
So when using it, you can weigh it according to your own situation. I personally use nvm to control the node version.

nvm uses

View available versions

nvm ls-remote

View installed version

nvm ls

Install a specified version

nvm install <version>

The version above can specify the version number listed in nvm ls-remote

Delete the specified version

nvm use <version>

n Installation

npm install -g n

Of course, you can also go to github to download your source code and compile it locally

$ git clone https://github.com/visionmedia/n.git
$ cd n
$ [sudo] make install
n 安装指定版本
n stable/laster/< version>

After n, add a symbol stable to identify the latest stable version, laster to identify the latest version, 3d689bd3819ead35ed794427bd12f459 that is, you can specify a version number

n 使用一个版本
n use <version>

n 删除一个版本
n rm <version>