How can I check if a string is null or empty in PowerShell?

Question

Is there a built-in IsNullOrEmpty-like function in order to check if a string is null or empty, in PowerShell?

I could not find it so far and if there i

Answer 1

I have a PowerShell script I have to run on a computer so out of date that it doesn't have [String]::IsNullOrWhiteSpace(), so I wrote my own.

function IsNullOrWhitespace($str)
{
    if ($str)
    {
        return ($str -replace " ","" -replace "`t","").Length -eq 0
    }
    else
    {
        return $TRUE
    }
}