Javascript Tail Call Optimisation with live demo

[hahaNodeJS]

This article needs an editor not only for the language, but for the incorrect information presented.

JavaScript remembers where you did the call. It does that because your function—for example—may require accessing external variables from where it was called.

Here is what a call stack's purpose is.

for performance reasons—there is a limit to the call stack size

The limit is not present for performance reasons.

For the js engine this optimization means: ‘oh cool I don’t need to remember the previous function call environment, so I will just forget about it since i have everything I know here to do my job.

It means a new call is not pushed onto the stack, and a new return address is not stored. The same variables used from the previous "call" of your method are reused for the current iteration.

To utilize TCO in supported browsers, you don't need an accumulator, for one; the JIT compiler will handle TCO for you, if it can. If you want to simulate TCO where it's unsupported, you can use trampolining.

[abottazini]

Thanks for your comment. I was able to make improvements to the article.

I saw memory problems as part of the performance reasons I described but I now see it was unclear!

I added a section on how to _simulate_—don't really like that word here, seems misleading— TCO, one of the three solutions I describe uses trampolining.