Changing table row color per two rows

Question

I have an HTML table and would like to change the row color every two rows, for two rows at a time. I don't mean selecting every other row using nth-child(even), which is all I keep seeing in my search engine results. I'm trying to set the background color of rows 1 and 2, then 5 and 6, then 9 and 10...and so on, leaving the other rows with the default white background.

I've tried using :nth-child(2n+b) and I don't think it's possible using that pseudo-selector. The tables are dynamically generated and will fluctuate in row count, so hard coding is not an option.

Is there some sort of JavaScript way to do this?

Answer 1

It's definitely possible using CSS's :nth-child() notation:

tr:nth-child(4n + 1) td,
tr:nth-child(4n + 2) td {
    background-color: #ffa;
}

tr:nth-child(4n + 3) td,
tr:nth-child(4n + 4) td {
    background-color: #f90;
}

JS Fiddle demo.