Powershell script to create seperate a node and npm environment for a project without the need to have it installed on the machine. This aids development with node and npm based tools for web development on windows. This script will launch a powershell enviroment with node and npm setup for the project.

BootstrapNode.ps1

function download_node {
    param([string]$node_directory, [string]$node_version)

    $node_exe = (Join-Path $node_directory "node.exe")
    if (Test-Path $node_exe) {
        Write-Host "Doing nothing as $node_exe exists"
        return
    }

    if (!$node_version) {
        $versions = (Invoke-WebRequest https://nodejs.org/download/release/index.json | ConvertFrom-Json) 
        $node_version=($versions | Where-Object { $_.lts -ne $false } | Sort-Object version | Select-Object -Last 1).version
    }

    $dir = "win-x86"
    if ($ENV:PROCESSOR_ARCHITECTURE -contains '64') 
    {
        $dir = "win-x64"
    }

    $download_url="https://nodejs.org/download/release/$node_version/$dir/node.exe"

    Write-Host "Ensuring $node_directory exists"
    New-Item -ItemType Directory -Force -Path "$node_directory" >$null

    Write-Host "Downloading $download_url to $node_directory"
    Invoke-WebRequest $download_url -OutFile $node_exe

}

function download_npm {
    param([string]$node_directory, [string]$npm_url)

    if (Test-Path (Join-Path $node_directory "npm.cmd")) {
        Write-Host "Doing nothing as npm.cmd exists within $node_directory"
        return
    }

    if (!$npm_url) {
        $npm_url=(Invoke-WebRequest https://api.github.com/repos/npm/npm/releases/latest | ConvertFrom-Json).zipball_url
    }

    $node_modules_dir = (Join-Path $node_directory "node_modules")
    $new_dir = (Join-Path $node_modules_dir "npm")
    if (Test-Path $new_dir) {
        Remove-Item -Recurse -Force -Path $new_dir >$null
    }

    $npm_zip_file = (Join-Path $node_directory "npm.zip")
    Write-Host "Downloading $npm_url to $node_directory"
    Invoke-WebRequest $npm_url -OutFile $npm_zip_file

    [Reflection.Assembly]::LoadWithPartialName('System.IO.Compression.FileSystem')
    $zip_file = [IO.Compression.ZipFile]::OpenRead($npm_zip_file)
    $unzip_directory = ($zip_file.Entries | Select -First 1).FullName
    [System.IO.Compression.ZipFile]::ExtractToDirectory($npm_zip_file, $node_directory);
    $zip_file.Dispose();

    New-Item -ItemType Directory -Force -Path $node_modules_dir >$null

    $original_dir = (Join-Path $node_directory $unzip_directory)
    $new_dir = (Join-Path $node_modules_dir "npm")

    Write-Host "Moving npm from $original_dir to $new_dir"
    Move-Item  $original_dir $new_dir

    Write-Host "Copying npm.cmd to $node_directory"
    Copy-Item (Join-Path (Join-Path $new_dir "bin") "npm.cmd") $node_directory

    Write-Host "Removing npm zip file"
    Remove-Item $npm_zip_file
}

if (!$node_directory) {
    $node_directory = (Join-Path $PSScriptRoot "bin")
}

download_node $node_directory
download_npm $node_directory

$original_path = ($env:PATH.Split(";") | Where-Object { $_ -notmatch  'node' -and $_ -ne ''})


Write-Host "Munging Path to ensure npm and node are in the correct place"
$env:PATH = (@($node_directory) + $original_path) -join ";"

Write-Host "Startup Complete! The directory $node_directory can be checked in to source control to ensure consistent versions"
Write-Host "Enjoy the node and npm commands"
$host.enternestedprompt()

Write-Host "Exiting environment"