Although JavaScript supports callbacks model very well, it currently doesnвЂ™t support tail-call optimization through CPS. When using callbacks there is no need for return statements and so the compiler can optimize recursive calls. In some functional languages, tail-call optimization can also be achieved using continuation-passing style (CPS) - a.k.a callbacks. The consequence of this is that once you are ready to perform your next recursive step, you donвЂ™t need the current stack frame anymore. Basically, the return value of any given recursive step is the same as the return value of the next recursive call. This results in the last recursive call simply returning accumulated value when the condition is met. To transform the implementation into tail-recursion, you perform your calculations first, and then you execute the recursive call, passing the results of your current step to the next recursive step. In this way, you donвЂ™t get the result of your calculation until you have returned from every recursive call. So in the first non-tail optimized implementation, you perform your recursive calls first, and then you take the return value of the recursive call and calculate the result.

Copy function sum ( a ) ДЄs you can see, instead of taking the return value and calculating the result after the recursive call returns, we calculate it first and pass along to the next recursive call. This article will introduce and explain a number of topics and ideas that will help you when practicing recursive problems. its not just wrong its utterly backwards. Considering 99 of programming is knowing recursion. Do keep trying to understand it because it WILL help you, just dont stress over it. But it does not have to be difficult.ДЄlthough recognizing the recursive nature of a problem and coming up with a solution requires a bit of an instinct, it can be learned through practice. The recursive solutions (if done well) do tend to be fairly efficient though. The number of questions on the web asking why recursion or recursive programs are so difficult to understand may give you an impression that recursion is indeed an advanced technique. Books often introduce it much later than iterative control structures. Recursion is one of the most important ideas in computer science, but itвЂ™s usually viewed as one of the harder parts of programming to grasp. Most new programmers learn iterative control structures first.Д«ut there is another very powerful control structure: recursion. I was surprised because I knew that the concept of recursion was not difficult.вЂќ - DijkstraвЂ™s keynote address of 1 March 1999ДЄlmost every programming language has various control structures like ifвЂ¦else/ switchвЂ¦ case blocks and iterative structures like for and while loops. вЂњ вЂ¦and discovered to my surprise that 10 % of my audience had the greatest difficulty in coping with the concept of recursive procedures.

You dont know js recursion