fix fecs warn: script was used before it was defined

Author: erik168

src/js.js

@@ -10,6 +10,16 @@
 // 只能暂时使用具名id
 define('js', {
     load: function (resourceId, req, load) {
+        var script = document.createElement('script');
+        script.src = req.toUrl(resourceId);
+        script.async = true;
+        if (script.readyState) {
+            script.onreadystatechange = onload;
+        }
+        else {
+            script.onload = onload;
+        }
+
         function onload() {
             var readyState = script.readyState;
             if (
@@ -22,16 +32,6 @@ define('js', {
             }
         }
 
-        var script = document.createElement('script');
-        script.src = req.toUrl(resourceId);
-        script.async = true;
-        if (script.readyState) {
-            script.onreadystatechange = onload;
-        }
-        else {
-            script.onload = onload;
-        }
-
         var parent = document.getElementsByTagName('head')[0]
             || document.body;
         parent.appendChild(script) && (parent = null);