codemirror.cljs

(defn code-mirror
  "Create a code-mirror editor. The parameters:
  value-atom (reagent atom)
    when this changes, the editor will update to reflect it.
  options
  :style (reagent style map)
    will be applied to the container element
  :js-cm-opts
    options passed into the CodeMirror constructor
  :on-cm-init (fn [cm] -> nil)
    called with the CodeMirror instance, for whatever extra fiddling you want to do."
  [value-atom {:keys [style
                      js-cm-opts
                      on-cm-init]}]

  (let [cm (atom nil)]
    (r/create-class
     {:component-did-mount
      (fn [this]
        (let [el (r/dom-node this)
              inst (js/CodeMirror.
                    el
                    (clj->js
                     (merge
                      {:lineNumbers false
                       :viewportMargin js/Infinity
                       :matchBrackets true
                       :autofocus true
                       :value @value-atom
                       :autoCloseBrackets true
                       :mode "clojure"}
                      js-cm-opts)))]

          (reset! cm inst)
          (.on inst "change"
               (fn []
                 (let [value (.getValue inst)]
                   (when-not (= value @value-atom)
                     (on-change value)))))
          (when on-cm-init
            (on-cm-init inst))
          ))

      :component-did-update
      (fn [this old-argv]
        (when-not (= @value-atom (.getValue @cm))
          (.setValue @cm @value-atom)
          ;; reset the cursor to the end of the text, if the text was changed externally
          (let [last-line (.lastLine @cm)
                last-ch (count (.getLine @cm last-line))]
            (.setCursor @cm last-line last-ch))))

      :reagent-render
      (fn [_ _ _]
        @value-atom
        [:div {:style style}])})))

http://stackoverflow.com/questions/13744176/codemirror-autocomplete-after-any-keyup
https://codemirror.net/demo/tern.html