memo.cljs

(def dt-a (js/Date. "2020-05-01"))
(def dt-b (js/Date. "2020-05-30"))
(def mills<->days (* 1000 60 60 24))

(defn get-duration
  "2つの日付の差分（日数）を求める"
  [dt-a dt-b]
  (/ (- dt-b dt-a) mills<->days))

(get-duration dt-a dt-b) ;-> 29


(def today
  "今日の日付"
  (let [now (js/Date.)
        year (.getFullYear now)
        month (inc (.getMonth now))
        date (.getDate now)]
    (js/Date. (str year "/" month "/" date))))