npm install doesn't work in Windows PowerShell

For me, it was much easier to do this in Powershell.

$env:Path += ";C:\Program Files\nodejs\"

Ran "npm" in powershell, and came up straight away.

node.js powershell npm

Use .npmrc to set the prefix explicitly:

Go to \Users\%USERNAME%\.npmrc. For example, in Powershell:
```
Notepad "\Users\$env:USERNAME\.npmrc"
```
Set the prefix:
```
prefix = "C:/Program Files/nodejs" 
```

References

CodeHunter