Add cmd.exe installer script

[MarkTiedemann]

Why?

• Because cmd.exe is still the default Windows command prompt which, arguably, makes it more user-friendly to run the installer in cmd.exe rather than powershell.exe.
• More choices for our users: Some people dislike cmd, some dislike powershell. By providing both, more people are gonna be happy, potentially.
• Because we can. :)

How?

In order to do this, the .cmd installer would have to have the same capabilities as the .ps1 installer. Some of these are:

• Download files via Invoke-WebRequest
• Extract a .zip archive via Expand-Archive or [System.IO.Compression.ZipFile]::ExtractToDirectory
• Add to the session's %Path% via $Env:Path and to the user's %Path% via [System.Environment]::SetEnvironmentVariable

As brought up in #153, since early 2018, curl and tar are available on Windows 10 by default. Thus, on a modern Windows 10 installation, curl could be used to download files and tar could be used to extract a .zip file.

Here's a short example:

@echo off
rem Determine latest Deno version
for /f "delims=/ tokens=6" %%v in ('"curl -s https://github.com/denoland/deno/releases | findstr \/denoland/deno/releases/download/.*/deno-x86_64-pc-windows-msvc.zip | findstr /n . | findstr ^1:"') do (
    rem Download latest Deno .zip file
    curl -Lo deno.zip https://github.com/denoland/deno/releases/download/%%v/deno-x86_64-pc-windows-msvc.zip
    rem Extract .zip file
    tar xf deno.zip
)

Manipulating the session %Path% can be done via set Path=... (or path). Manipulating the users's %Path% can be done using reg, reading and writing to the Path value of the HKEY_CURRENT_USER\Environment registry path.

Note that I'm not suggesting to drop the PowerShell installer, I'm simply suggesting that we could add an additional Command Prompt installer.

[MarkTiedemann]

Here's a random experiment on how you could distribute a "one-line batch installer": https://github.com/MarkTiedemann/deno-batch-installer