Calculating factorials is important for mathematical computations, combinatorics, probability calculations, and implementing features like permutation generators or statistical analysis in JavaScript applications. With over 25 years of experience in software development and as the creator of CoreUI, I’ve implemented factorial calculations in components like mathematical utilities, educational tools, and data analysis features where precise mathematical operations are essential for accurate results. From my extensive expertise, the most straightforward approach for small numbers is using recursion, while iteration provides better performance and avoids stack overflow for larger numbers. Both methods have their place depending on the use case and performance requirements.