$url = "https://api.vk.com/method/friends.get?user_id=42340497&fields=nickname"
$json = Invoke-WebRequest -Uri $url | ConvertFrom-Json |
ForEach-Object {
    foreach ($property in ($_ | Get-Member -MemberType NoteProperty))
    {
        $_.$($property.Name) |
        Add-Member -MemberType NoteProperty -Name 'Name' -Value $property.Name -PassThru
    }
}


foreach( $uid in $json )
{
    "https://vk.com/id"+$uid.uid.ToString() >> e:\friends.txt
}