ClojureScript - convert arbitrary JavaScript object to Clojure Script map

js->clj only works for Object, anything with custom constructor (see type) will be returned as is.

see: https://github.com/clojure/clojurescript/blob/master/src/main/cljs/cljs/core.cljs#L9319

I suggest doing this instead:

(defn jsx->clj
  [x]
  (into {} (for [k (.keys js/Object x)] [k (aget x k)])))

UPDATE for correct solution see Aaron's answer, gotta use goog.object


The accepted answer wasn't working for me with the javascript object window.performance.timing. This is because Object.keys() doesn't actually return the props for the PerformanceTiming object.

(.keys js/Object (.-timing (.-performance js/window))
; => #js[]

This is despite the fact that the props of PerformanceTiming are indeed iterable with a vanilla JavaScript loop:

for (a in window.performance.timing) {
  console.log(a);
}
// navigationStart
// unloadEventStart
// unloadEventEnd
// ...

The following is what I came up with to convert an arbitrary JavaScript object to a ClojureScript map. Note the use of two simple Google Closure functions.

  • goog.typeOf wraps typeof, which isn't normally accessible to us in ClojureScript. I use this to filter out props which are functions.
  • goog.object.getKeys wraps for (prop in obj) {...}, building up an array result which we can reduce into a map.

Solution (flat)

(defn obj->clj
  [obj]
  (-> (fn [result key]
        (let [v (goog.object/get obj key)]
          (if (= "function" (goog/typeOf v))
            result
            (assoc result key v))))
      (reduce {} (.getKeys goog/object obj))))

Solution (recursive)

Update: This solution will work for nested maps.

(defn obj->clj
  [obj]
  (if (goog.isObject obj)
    (-> (fn [result key]
          (let [v (goog.object/get obj key)]
            (if (= "function" (goog/typeOf v))
              result
              (assoc result key (obj->clj v)))))
        (reduce {} (.getKeys goog/object obj)))
    obj))