Compare loop performance

Testing the performance of using `delete` keyword VS setting prop to null to remove an property of an object

test

https://www.linkedin.com/pulse/25-techniques-javascript-performance-optimization-steven-de-salas When making calls to modify DOM make sure you batch them up so as to avoid repeated screen rendering, for example when applying styling changes. The ideal approach here is to make many styling changes in one go by adding or removing a class, rather than apply each individual style separately. This is because every DOM change prompts the browser to re-render the whole UI using the boxing model. If you need to move an item across the page using X+Y coordinates, make sure that these two are applied at the same time rather than separately.

Iterative and recursive versions Implementations borrowed from https://medium.freecodecamp.org/how-to-factorialize-a-number-in-javascript-9263c89a4b38