Linear animation generator for Om & React

gistfile1.clj

(defn animate-value
  [start-val end-val duration]
  (let [decrement? (< end-val start-val)
        transmit-chan (chan)
        cancel-chan (chan)
        animation-interval 40 ;40 ms interval - 25fps
        steps (/ duration animation-interval)
        full-range (- start-val end-val)
        per-step (util/abs (/ full-range steps))
        state (atom start-val)
        animator (js/setInterval
                  (fn []
                    (let [update-fn (if decrement?
                                      #(- % per-step)
                                      #(+ % per-step))]
                      (swap! state update-fn))
                    (put! transmit-chan @state)
                    (put! cancel-chan @state))
                  animation-interval)
        ]
    (go
     (loop []
       (let [value (<! cancel-chan)]
         (when value
           (when ((if decrement? <= >=) value end-val)
             (js/clearInterval animator)
             (put! transmit-chan end-val) ;In case we overshoot
             (close! transmit-chan)
             (close! cancel-chan))
           (recur)))))
    transmit-chan
    ))

Quick function to generate a linearly increasing/decreasing value across a range - timing is handled internally, so you can just read the output value in a go loop and feed that value straight to om/transact! or om/update-state! in order to animate the component property.