STYLE_GUIDE.md

Requirements

• One True Brace Style (OTBS)
• No aliases (GCI, ?, %, etc.)
• Meaningful variable names (not $A, $Var1, etc.)
• Indentation. IDEs like Visual Studio Code will help you with this.

Recommendations

Lists instead of arrays

Using an ArrayList or List[T] is a lot faster than regular arrays, especially when you're dealing with a lot of data. https://foxdeploy.com/2016/03/23/coding-for-speed/

Use this:

$MyArray = New-Object System.Collections.ArrayList
For ( $Count = 1; $Count -le 10000000; $Count ++ ) {
    $null = $MyArray.Add($Count)
}

or this:

$MyArray = New-Object System.Collections.Generic.List[object]
For ( $Count = 1; $Count -le 10000000; $Count ++ ) {
    $MyArray.Add($Count)
}

instead of this:

$MyArray = @()
For ( $Count = 1; $Count -le 10000000; $Count ++ ) {
    $MyArray += $Count
}

Do not compare to $null

Using $null comparisons can have strange unwanted consequences. It's usually best to avoid it altogether.

Use this:

$Drives = Get-ItemProperty "Registry::HKEY_USERS\*\Network\*"
if ( $Drives ) {
    Do-FancyThings
}

or this:

$Drives = Get-ItemProperty "Registry::HKEY_USERS\*\Network\*"
if ( $null -ne $Drives ) {
    Do-FancyThings
}

instead of this:

$Drives = Get-ItemProperty "Registry::HKEY_USERS\*\Network\*"
if ( $Drives -ne $null ) {
    Do-FancyThings
}

Use functions for reused code

If you find yourself copying and pasting a chunk of your code with only minor changes, you should probably use a function instead.

Use this:

function Download-File {
    param (
        [String]$FileName
    )

    if ( -Not ( Test-Path $FileName ) ) {
        Invoke-RestMethod "https://mywebsite.tld/$FileName"
    }
}

Download-File -FileName "File1.exe"
Download-File -FileName "File2.exe"

instead of this:

if ( -Not ( Test-Path "File1.exe" ) ) {
    Invoke-RestMethod "https://mywebsite.tld/File1.exe"
}
if ( -Not ( Test-Path "File2.exe" ) ) {
    Invoke-RestMethod "https://mywebsite.tld/File2.exe"
}

Do not use Out-Null to erase output

In PowerShell versions 1 through 5, Out-Null is slower than $null = or [void] and while this won't make a large performance difference for most scripts we'd prefer to use the technically better option.

Use this:

$null = Install-Module -Name "FancyPants" -Force

or this:

$MyArray = New-Object System.Collections.ArrayList
[void]$MyArray.Add(1)

instead of this:

Install-Module -Name "FancyPants" -Force | Out-Null