(let [canvas (js/document.getElementById "canvas-1")
ctx (.getContext canvas "2d")
width (.-width canvas)
height (.-height canvas)]
(set! (.-fillStyle ctx) "red")
(.clearRect ctx 0 0 width height)
(.fillRect ctx 0 0 width height)
(set! (.-fillStyle ctx) "blue")
(.fillRect ctx 100 100 50 50)
)