this can be done easily with  a vbs code (as i'm not so familiar with js ) 
<input type="button" id="btn" Value="Close" onclick="check">
<script Language="VBScript">
sub check
if btn.Value="Close" then btn.Value="Open" 
end sub
</script>
and you're done , however this changes the Name to display only and does not change the function {onclick} , i did some researches on how to do the second one and seem there isnt' something like
btn.onclick = ".."
but i figured out a way using <"span"> tag it goes like this :
<script Language="VBScript">
  Sub function1
  MsgBox "function1"
  span.InnerHTML= "<Input type=""button"" Value=""button2"" onclick=""function2"">"
  End Sub
   Sub function2
  MsgBox "function2"
  span.InnerHTML = "<Input type=""button"" Value=""button1"" onclick=""function1"">"
  End Sub
  </script>
  <body>
  <span id="span" name="span" >
  <input type="button" Value="button1" onclick="function1">
  </span>
  </body>
try it yourself , change the codes in sub function1 and sub function2, basically all you need to know to make it in jscript is the line 
span.InnerHTML = "..." 
the rest is your code you wanna execute
hope this helps :D