JavaScript’s reduce is one of the most useful array methods that should be in a developer’s arsenal. Introduced in ES5, it’s somewhat similar to for…each and map methods that are used with ...

The reduce takes a two-argument function, where the first argument is the accumulator—a variable that will live across all iterations, ultimately becoming the output of the reduce call.

In part 2 of the article below, we focus on a response by pharmaceutical manufacturers to reduce costs—programs called accumulators and maximizers. Pharmacy benefit managers ...