class.cljs

(defn Greeter [greeting]
  (this-as this
    (set! (.-greeting this) greeting)
    this))

(specify! (.-prototype Greeter)
  Object
  (greet [this name]
    (str (.-greeting this) ", " name)))

(let [greeter (Greeter. "Hello")]
  (println (.greet greeter "John")))