nthchildn

Nthchildn is a generalized selector concept used to identify elements by their ordinal position among siblings. It extends the idea of ordinal selectors by parameterizing the position with two integers, typically described as a (step) and b (offset). In theory, an element matches nthchildn(a, b) if its one-based index within its parent satisfies the pattern an + b for some integer n.

Syntax and examples

The concept is described as selecting elements whose index matches an + b. For example, nthchildn(3, 2) would target the 2nd, 5th, 8th, and so on, within each parent. Another example, nthchildn(2, 1), would select the 1st, 3rd, 5th positions, etc. In actual CSS, these patterns correspond to the standard :nth-child(an + b) syntax, such as :nth-child(3n+2) or :nth-child(2n+1).

Usage and scope

Nthchildn is not an official CSS selector. It appears mainly as a theoretical notation in discussions, design documents, or as a teaching device to describe patterns of element ordering. It can be useful for planning styling rules, data extraction logic, or documentation that needs a compact way to describe regular position-based selections.

Limitations and compatibility

There is no standard browser implementation of a named nthchildn selector. Real-world usage relies on the standard CSS :nth-child(an+b) syntax or on custom selector engines in libraries. For practical styling, use the established :nth-child syntax or equivalent scripting logic.

See also

nth-child, CSS selectors, pseudo-classes.