Will you good people be kind enough to translate this language to 
javascript. 
Thanx
Ade'
   
 <SCRIPT LANGUAGE = "VBScript">
Dim frm1

Sub Window_OnLoad
	Set frm1 = Document.thisform
End Sub

Sub txtFrom_OnBlur
	If Not IsDate(frm1.txtFrom.Value) Then
		Alert "Please enter a valid date"
		frm1.txtFrom.focus
	End If
End Sub

Sub txtUntil_OnBlur
	If Not IsDate(frm1.txtUntil.value) Then
		Alert "Please enter a valid date"
		frm1.txtUntil.Focus
	End If
End Sub


Function IsFieldaDate(field)
	If Not IsDate(field.value) Then
		Alert "Entry must be a date - Action Cancelled"
		field.focus
		IsFieldaDate = False
	Else
		IsFieldaDate = True
	End If
End Function


Function thisform_OnSubmit
	Set ChkField = frm1.txtFrom
	If Not IsFieldaDate(ChkField) Then
		thisform_OnSubmit = False
		Exit Function
	End If

	Set ChkField = frm1.txtUntil
	If Not IsFieldaDate(ChkField) Then
		thisform_OnSubmit = False
		Exit Function
	End If

	thisform_OnSubmit = True
End Function
</SCRIPT>