add PullRefresh component

docs/src/doc.config.js

@@ -176,6 +176,10 @@ module.exports = {
                 "path": "/picker",
                 "title": "Picker 选择器"
               },
+              {
+                "path": "/pull-refresh",
+                "title": "PullRefresh 下拉刷新"
+              },
               {
                 "path": "/toast",
                 "title": "Toast 轻提示"

docs/src/iframe-router.js

@@ -23,18 +23,19 @@ window.changePath = function(path) {
 
 function iframeReady(iframe, callback) {
   const doc = iframe.contentDocument || iframe.contentWindow.document;
+  const interval = () => {
+    if (iframe.contentWindow.changePath) {
+      callback();
+    } else {
+      setTimeout(() => {
+        interval();
+      }, 50);
+    }
+  };
+
   if (doc.readyState === 'complete') {
-    callback();
+    interval();
   } else {
-    const interval = () => {
-      if (iframe.contentWindow.changePath) {
-        callback();
-      } else {
-        setTimeout(() => {
-          interval();
-        }, 50);
-      }
-    };
     iframe.onload = interval;
   }
 }