Self-describing numbers

You are encouraged to solve this task according to the task description, using any language you may know.
There are several so-called "self-describing" or "self-descriptive" integers.

An integer is said to be "self-describing" if it has the property that, when digit positions are labeled 0 to N-1, the digit in each position is equal to the number of times that that digit appears in the number.

For example,   2020   is a four-digit self describing number:

   position   0   has value   2   and there are two 0s in the number;
   position   1   has value   0   and there are no 1s in the number;
   position   2   has value   2   and there are two 2s;
   position   3   has value   0   and there are zero 3s.


Self-describing numbers < 100.000.000  are:     1210,   2020,   21200,   3211000,   42101000.



Task Description
 Write a function/routine/method/... that will check whether a given positive integer is self-describing.
 As an optional stretch goal - generate and display the set of self-describing numbers.


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Function IsSelfDescribing(n)
	IsSelfDescribing = False
	Set digit = CreateObject("Scripting.Dictionary")
	For i = 1 To Len(n)
		k = Mid(n,i,1)
		If digit.Exists(k) Then
			digit.Item(k) = digit.Item(k) + 1
		Else
			digit.Add k,1
		End If	
	Next
	c = 0
	For j = 0 To Len(n)-1
		l = Mid(n,j+1,1)
		If digit.Exists(CStr(j)) Then
			If digit.Item(CStr(j)) = CInt(l) Then
				c = c + 1
			End If
		ElseIf l = 0 Then
			c = c + 1
		Else
			Exit For
		End If
	Next
	If c = Len(n) Then
		IsSelfDescribing = True
	End If
End Function
 
'testing
start_time = Now
s = ""
For m = 1 To 100000000
	If 	IsSelfDescribing(m) Then
		WScript.StdOut.WriteLine m
	End If
Next
end_time = Now
WScript.StdOut.WriteLine "Elapse Time: " & DateDiff("s",start_time,end_time) & " seconds"
 