blah.cljs

(em/defaction resize-div [width]
  "#rz-demo" (ef/chain
               (ef/resize width :curheight 500)
               (ef/resize 5 :curheight 500)))

(em/defaction setup []
  "#button2" (ef/listen #(resize-div 200)))

(em/defaction init []
  #(do
     (start)
     (user-registration)
     (post-button)
     (setup)
     ;(menu)
     ;(repl/connect "http://localhost:9000/repl")
     ))

(set! (.-onload js/window) init)

index.html

 <div class="row">
      <div id="snippet">
          <button id="button2">click me</button>

          <div id="rz-demo" style="width: 5px; height: 10px; background-color: #33ff33;"> </div>
    </div>
      </div>
  </div>