Add PowerShell install script

README.md

@@ -4,9 +4,18 @@
 |:---------------:|:-----------:|
 | [![Build Status](https://travis-ci.com/denoland/deno_install.svg?branch=master)](https://travis-ci.com/denoland/deno_install) | [![Build status](https://ci.appveyor.com/api/projects/status/gtekeaf7r60xa896?svg=true)](https://ci.appveyor.com/project/deno/deno-install) |
 
-Downloads the latest Deno binary into $HOME/.deno/bin
+Downloads the latest Deno binary into `$HOME/.deno/bin`.
+
+**Install with Python:**
 
-Usage:
 ```
 curl -sSf https://raw.githubusercontent.com/denoland/deno_install/master/install.py | python
 ```
+
+**Install with PowerShell:**
+
+```powershell
+iex (iwr https://raw.githubusercontent.com/denoland/deno_install/master/install.ps1)
+```
+
+_Note: Depending on your security settings, you may have to run `Set-ExecutionPolicy RemoteSigned -Scope CurrentUser` first to allow downloaded scripts to be executed._

install.ps1

@@ -0,0 +1,82 @@
+# Copyright 2018 the Deno authors. All rights reserved. MIT license.
+# TODO(everyone): Keep this script simple and easily auditable.
+
+$ErrorActionPreference = "Stop"
+
+# Enable TLS 1.2 since it is required for connections to GitHub.
+[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
+
+# Helper functions for pretty terminal output.
+function Write-Part ([string] $Text) {
+  Write-Host $Text -NoNewline
+}
+function Write-Emphasized ([string] $Text) {
+  Write-Host $Text -NoNewLine -ForegroundColor "Yellow"
+}
+function Write-Done {
+  Write-Host " done" -NoNewline -ForegroundColor "Green";
+  Write-Host "."
+}
+
+# Determine latest Deno release via GitHub API.
+$latest_release_uri = "https://api.github.com/repos/denoland/deno/releases/latest"
+Write-Part "Downloading "; Write-Emphasized $latest_release_uri; Write-Part "..."
+$latest_release_json = Invoke-WebRequest -Uri $latest_release_uri
+Write-Done
+
+Write-Part "Determining latest Deno release: "
+$latest_release = ($latest_release_json | ConvertFrom-Json).tag_name
+Write-Emphasized $latest_release; Write-Part "... "
+Write-Done
+
+# Create ~\.deno\bin directory if it doesn't already exist
+$deno_dir = "${Home}\.deno\bin"
+if (-not (Test-Path $deno_dir)) {
+  Write-Part "Creating directory "; Write-Emphasized $deno_dir; Write-Part "..."
+  New-Item -Path $deno_dir -ItemType Directory | Out-Null
+  Write-Done
+}
+
+# Download latest Deno release.
+$zip_file = "${deno_dir}\deno_win_x64.zip"
+$download_uri = "https://github.com/denoland/deno/releases/download/" +
+                "${latest_release}/deno_win_x64.zip"
+Write-Part "Downloading "; Write-Emphasized $download_uri; Write-Part "..."
+Invoke-WebRequest -Uri $download_uri -OutFile $zip_file
+Write-Done
+
+# Extract deno.exe from .zip file.
+Write-Part "Extracting "; Write-Emphasized $zip_file
+Write-Part " into "; Write-Emphasized ${deno_dir}; Write-Part "..."
+# Using -Force to overwrite deno.exe if it already exists
+Expand-Archive -Path $zip_file -DestinationPath $deno_dir -Force
+Write-Done
+
+# Remove .zip file.
+Write-Part "Removing "; Write-Emphasized $zip_file; Write-Part "..."
+Remove-Item -Path $zip_file
+Write-Done
+
+# Get Path environment variable for the current user.
+$user = [EnvironmentVariableTarget]::User
+$path = [Environment]::GetEnvironmentVariable("PATH", $user)
+
+# Check whether Deno is in the Path.
+$paths = $path -split ";"
+$is_in_path = $paths -contains $deno_dir -or $paths -contains "${deno_dir}\"
+
+# Add Deno to PATH if it hasn't been added already.
+if (-not $is_in_path) {
+  Write-Part "Adding "; Write-Emphasized $deno_dir; Write-Part " to the "
+  Write-Emphasized "PATH"; Write-Part " environment variable..."
+  [Environment]::SetEnvironmentVariable("PATH", "${path};${deno_dir}", $user)
+  # Add Deno to the PATH variable of the current terminal session
+  # so `deno` can be used immediately without restarting the terminal.
+  $env:PATH += ";${deno_dir}"
+  Write-Done
+}
+
+Write-Host ""
+Write-Host "Deno was installed successfully." -ForegroundColor "Green"
+Write-Part "Run "; Write-Emphasized "deno --help"; Write-Host " to get started."
+Write-Host ""