[jQuery] Increment Value. What am I doing wrong?

[jQuery] Increment Value. What am I doing wrong?


Hello,
I have an input on my page as follows:
<input id="Index" name="Index" type="hidden" value="0" />
I am trying to increase and decrease the value of the input as
follows:
$index = $('#Index');
$index.val()--;
I always get an error:
invalid assignment left-hand side
What am I doing wrong?
Thanks,
Miguel