Changing an element's ID with jQuery

Question

I need to change an element's ID using jQuery.

Apparently these don't work:

jQuery(this).prev("li").attr("id")="newid" jQuery(this).prev("li")="newid" 

I found out that I can make it happen with the following code:

jQuery(this).prev("li")show(function() {     this.id="newid"; }); 

But that doesn't seem right to me. There must be a better way, no? Also, in case there isn't, what other method can I use instead of show/hide or other effects? Obviously I don't want to show/hide or affect the element every time, just to change its ID.

(Yep, I'm a jQuery newbie.)

Edit
I can't use classes in this case, I must use IDs.

Answer 1

Your syntax is incorrect, you should pass the value as the second parameter:

jQuery(this).prev("li").attr("id","newId"); 

Answer 2

A PREFERRED OPTION over .attr is to use .prop like so:

$(this).prev('li').prop('id', 'newId'); 

.attr retrieves the element's attribute whereas .prop retrieves the property that the attribute references (i.e. what you're actually intending to modify)