Add deprecation notice for class.template returning a string

Load `Polymer.html` fn by default with `PolymerElement`.
Polymer · Dec 5, 2017 · 530a68b · 530a68b
1 parent bdfa5fc
commit 530a68b
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/lib/mixins/element-mixin.html b/lib/mixins/element-mixin.html
@@ -14,6 +14,7 @@
 <link rel="import" href="../utils/case-map.html">
 <link rel="import" href="../utils/style-gather.html">
 <link rel="import" href="../utils/resolve-url.html">
+<link rel="import" href="../utils/html-fn.html">
 <link rel="import" href="../elements/dom-module.html">
 <link rel="import" href="property-effects.html">
 
@@ -270,6 +271,8 @@
       let template = /** @type {PolymerElementConstructor} */ (klass).template;
       if (template) {
         if (typeof template === 'string') {
+          console.warn('String templates are deprecated. ' +
+            `Please return a <template>, or use Polymer.html\`\` for element <${klass.is}>`);
           let t = document.createElement('template');
           t.innerHTML = template;
           template = t;

diff --git a/test/smoke/html-fn.html b/test/smoke/html-fn.html
@@ -12,7 +12,6 @@
 <head>
   <script src="../../../webcomponentsjs/webcomponents-lite.js"></script>
   <link rel="import" href="../../polymer-element.html">
-  <link rel="import" href="../../lib/utils/html-fn.html">
 </head>
 <body>
   <script>
@@ -50,6 +49,16 @@ <h3 id="name">${this.is}</h3>
     }
     customElements.define(SubClass.is, SubClass);
   </script>
+  <script>
+    class XString extends Polymer.Element {
+      static get is() {return 'x-string'};
+      static get template() {
+        return 'string template!';
+      }
+    }
+    customElements.define(XString.is, XString);
+  </script>
   <super-class></super-class>
   <sub-class></sub-class>
+  <x-string></x-string>
 </body>