Don't rename props for custom elements

Custom element names must always contain hyphen so we can use that to
keep track of which elements are native vs. custom when parsing tag
name.

Fixes #322

src/reagent/impl/template.cljs

@@ -71,25 +71,56 @@
                    (apply x args))
         :else (clj->js x)))
 
+;; Previous few functions copied for custom elements,
+;; without mapping from class to className etc.
+
+(def custom-prop-name-cache #js{})
+
+(defn cached-custom-prop-name [k]
+  (if (named? k)
+    (if-some [k' (cache-get custom-prop-name-cache (name k))]
+      k'
+      (aset prop-name-cache (name k)
+            (util/dash-to-camel k)))
+    k))
+
+(defn custom-kv-conv [o k v]
+  (doto o
+    (aset (cached-custom-prop-name k)
+          (convert-prop-value v))))
+
+(defn convert-custom-prop-value [x]
+  (cond (js-val? x) x
+        (named? x) (name x)
+        (map? x) (reduce-kv custom-kv-conv #js{} x)
+        (coll? x) (clj->js x)
+        (ifn? x) (fn [& args]
+                   (apply x args))
+        :else (clj->js x)))
+
 (defn oset [o k v]
   (doto (if (nil? o) #js{} o)
     (aset k v)))
 
 (defn oget [o k]
   (if (nil? o) nil (aget o k)))
 
-(defn set-id-class [p id-class]
+(defn set-id-class
+  "Takes the id and class from tag keyword, and adds them to the
+  other props. Parsed tag is JS object with :id and :class properties."
+  [props id-class]
   (let [id ($ id-class :id)
-        p (if (and (some? id)
-                   (nil? (oget p "id")))
-            (oset p "id" id)
-            p)]
-    (if-some [class ($ id-class :className)]
-      (let [old (oget p "className")]
-        (oset p "className" (if (nil? old)
-                              class
-                              (str class " " old))))
-      p)))
+        class ($ id-class :class)]
+    (cond-> props
+      ;; Only use ID from tag keyword if no :id in props already
+      (and (some? id)
+           (nil? (:id props)))
+      (assoc :id id)
+
+      ;; Merge classes
+      class
+      (assoc :class (let [old-class (:class props)]
+                      (if (nil? old-class) class (str class " " old-class)))))))
 
 (defn stringify-class [{:keys [class] :as props}]
   (if (coll? class)
@@ -100,10 +131,12 @@
     props))
 
 (defn convert-props [props id-class]
-  (-> props
-      stringify-class
-      convert-prop-value
-      (set-id-class id-class)))
+  (let [props (-> props
+                  stringify-class
+                  (set-id-class id-class))]
+    (if ($ id-class :custom)
+      (convert-custom-prop-value props)
+      (convert-prop-value props))))
 
 ;;; Specialization for input components
 
@@ -134,7 +167,7 @@
       ($! node :value rendered-value)
       (when (fn? on-write)
         (on-write rendered-value)))
-    
+
     ;; Setting "value" (below) moves the cursor position to the
     ;; end which gives the user a jarring experience.
     ;;
@@ -280,9 +313,12 @@
                 (string/replace class #"\." " "))]
     (assert tag (str "Invalid tag: '" hiccup-tag "'"
                      (comp/comp-name)))
-    #js{:name tag
-        :id id
-        :className class}))
+    #js {:name tag
+         :id id
+         :class class
+         ;; Custom element names must contain hyphen
+         ;; https://www.w3.org/TR/custom-elements/#custom-elements-core-concepts
+         :custom (not= -1 (.indexOf tag "-"))}))
 
 (defn try-get-key [x]
   ;; try catch to avoid clojurescript peculiarity with

test/reagenttest/testreagent.cljs

@@ -1064,3 +1064,12 @@
   (is (re-find #"<div style=\"text-align:center(;?)\">foo</div>"
                (server/render-to-static-markup
                  [:div {:style {:text-align "center"}} "foo"]))))
+
+(deftest custom-element-class-prop
+  (is (re-find #"<custom-element class=\"foobar\">foo</custom-element>"
+               (server/render-to-static-markup
+                 [:custom-element {:class "foobar"} "foo"])))
+
+  (is (re-find #"<custom-element class=\"foobar\">foo</custom-element>"
+               (server/render-to-static-markup
+                 [:custom-element.foobar "foo"]))) )