Powershell: How to insert a new alert

Sometimes for test I needed to insert a new alert in my application.

To accomplished this task I use the following script:

clear

$webAppUrl = Read-Host -Prompt "Url Web Application: "

if ($webAppUrl.Length -ile 0) {
    $webAppUrl = "http://yourSharepointSite"
}

$web = Get-SPWeb $webAppUrl

$userName = Read-Host -Prompt "Which user: "

$users = $web.Users

foreach ($user in $users) {
    if ($user.Name -ne $userName) {
        continue
    }
    
    $newAlert = $web.Alerts.Add()
    $newAlert.AlertType = "List";
    $newAlert.List = Read-Host -Prompt "Which list: "
    $newAlert.AlwaysNotify = False
    $newAlert.DynamicRecipient = "assignedTo";
    $newAlert.EventTypeBitmask = 3
    $newAlert.User = $user
    $newAlert.AlertFrequency = Read-Host -Prompt "Alert Frequency (Daily/Weekly): "
    
    $newAlert.Properties["SomeCustomProperties"] = "V_Value1;V_Value2"
    $newAlert.Title = "Alert from powershell"
    $newAlert.Update()
    Write-Host "Alert inserted"
}

bye