nth-child

Calculate the nth-child equation for CSS selectors.

For example, if you wanted to have a selector for every third child element (i.e. 1, 4, 7), you would use the selector nth-child(3n + 1). To calculate this we can take the first two numbers, 1 and 4, and pair them with 0 and 1, respectively. We treat each pair as an (x, y) coordinate pair where the desired children numbers are the y coordinates (i.e. (0, 1) and (1, 4)). We use these two coordinate pairs to calculate the linear equation that represents the nth-child selector.

Install

$ npm install -g nth-child

Usage

$ nth-child n1 n2

Examples

Target every child starting with the second child

$ nth-child 2 3
n + 2

Target every third child

$ nth-child 1 4
3n + 1

Target the first two children

$ nth-child 2 1
-n + 2