Selects even elements, zero-indexed. See also odd.
In particular, note that the 0-based indexing means that, counter-intuitively, :even selects the first element, third element, and so on within the matched set.
Because :even is a jQuery extension and not part of the CSS specification, queries using :even cannot take advantage of the performance boost provided by the native DOM querySelectorAll() method. To achieve the best performance when using :ev