areduce

macrosince v0.0-927 clojure.core/areduceEdit
(areduce a idx ret init expr)

Details:

For quickly reducing an expression expr across a JavaScript array a. The expression can use ret as the current result, which is initialized to init. It can also use idx to get the current index.

Examples:

(def a #js [1 2 3])
(areduce a i ret 0 (+ ret (aget a i)))
;;=> 6

See Also:

Source docstring:
Reduces an expression across an array a, using an index named idx,
and return value named ret, initialized to init, setting ret to the
evaluation of expr at each step, returning ret.
Source code @ clojurescript:src/main/clojure/cljs/core.cljc
(core/defmacro areduce
  [a idx ret init expr]
  `(let [a# ~a
         l# (alength a#)]
     (loop  [~idx 0 ~ret ~init]
       (if (< ~idx l#)
         (recur (inc ~idx) ~expr)
         ~ret))))