JavaScript: Functional Programming for JavaScript Developers

Accumulators

We've looked at some simple array functions which add filtering and pipes to arrays. Another useful tool is the accumulator. Accumulators aid in building up a single result by iterating over a collection. Many common operations such as summing up the elements of an array can be implemented using an accumulator instead of a loop.

Recursion is popular within functional programming languages and many of them actually offer an optimization called "tail call optimization". A language that supports this provides optimizations for functions using recursion in which the stack frame is reused. This is very efficient and can easily replace most loops. Details on whether tail call optimization is supported in any JavaScript interpreter are sketchy. ...