aset does not chain in clojurescript

Question

I found a result in clojurescript whon aset is chained:

(def data (js-obj))
(-> data 
    (aset "a" "a")
    (aset "b" "b"))

(aget data "a") ;=> "a"
(aget data "b") ;=> 'returns nothing'

whereas

(-> 1 inc dec) ;=> returns 1, which is fine

Answer 1

Ankur is right about why this happens; to "work around" it, you should use the more semantically-descriptive:

(doto data
      (aset "a" "a")
      (aset "b" "b"))

Answer 2

aset returns the inserted element and not the array object itself, hence in the case of "b" the data is not threaded to it from previous "a" call.