jQuery :even Selector
Select every other (even) <tr> element:
Definition and Usage
The :even selector selects each element with an even index number (like: 0, 2, 4, etc.).
The index numbers start at 0.
This is mostly used together with another selector to select every even indexed element in a group (like in the example above).
Tip: Use the :odd selector to select elements with odd index numbers.