compose Performs right-to-left function composition. Use Array.prototype.reduce() to perform right-to-left function composition. The last (rightmost) function can accept one or more arguments; the remaining functions must be unary. const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args))); const add5 = x => x + 5; const multiply = (x, y) => x * y; const multiplyAndAdd5 = compose( add5, multiply ); multiplyAndAdd5(5, 2); // 15