Add link to codepen in examples

examples/resources/common.js

@@ -18,6 +18,43 @@
     };
   }
 
+  var codepenButton = document.getElementById('codepen-button');
+  if (codepenButton) {
+    codepenButton.onclick = function(event) {
+      event.preventDefault();
+      var form = document.getElementById('codepen-form');
+
+      // Doc : https://blog.codepen.io/documentation/api/prefill/
+
+      var resources = form.resources.value.split(',');
+
+      var data = {
+        title: form.title.value,
+        description: form.description.value,
+        layout: 'left',
+        html: form.html.value,
+        css: form.css.value,
+        js: form.js.value,
+        css_external: resources.filter(function(resource) {
+          return resource.lastIndexOf('.css') === resource.length - 4;
+        }).join(';'),
+        js_external: resources.filter(function(resource) {
+          return resource.lastIndexOf('.js') === resource.length - 3;
+        }).join(';')
+      };
+
+      // binary flags to display html, css, js and/or console tabs
+      data.editors = '' + Number(data.html.length > 0) +
+          Number(data.css.length > 0) +
+          Number(data.js.length > 0) +
+          Number(data.js.indexOf('console') > 0);
+
+      form.data.value = JSON.stringify(data);
+
+      form.submit();
+    };
+  }
+
   if (window.location.host === 'localhost:3000') {
     return;
   }