composeRight Performs left-to-right function composition. Use Array.prototype.reduce() to perform left-to-right function composition. The first (leftmost) function can accept one or more arguments; the remaining functions must be unary. const composeRight = (...fns) => fns.reduce((f, g) => (...args) => g(f(...args))); const add = (x, y) => x + y; const square = x => x * x; const addAndSquare = composeRight(add, square); addAndSquare(1, 2); // 9