I am using jQuery and put this code in my javascript:
function HideMe(itemID) { var myDiv = \'item_\' + itemID; $(myDiv).fadeOut(\"slow\"); }
Also, you probably forgot a # in the selector (unless you've got something like in the markup).
#
var myDiv = '#item_' + itemID;
jQuery uses CSS selectors to search for elements, so without the #, you'd get every element with the tag item_x instead of the ID.
item_x