Differential comment previews.

webroot/rsrc/js/application/differential/behavior-comment-preview.js

@@ -0,0 +1,50 @@
+/**
+ * @provides javelin-behavior-differential-feedback-preview
+ * @requires javelin-lib-dev
+ */
+
+JX.behavior('differential-feedback-preview', function(config) {
+
+  var action = JX.$(config.action);
+  var content = JX.$(config.content);
+  var preview = JX.$(config.preview);
+
+  var aval = null;//action.value;
+  var cval = null;//content.value;
+  var defer = null;
+  var min = null;
+  var request = null;
+
+  function check() {
+    if (request || (min && (new Date().getTime() < min))) {
+      // Waiting on an async or just got one back, rate-limit.
+      return;
+    }
+
+    defer && defer.stop();
+
+    if (action.value !== aval || content.value !== cval) {
+      aval = action.value;
+      cval = content.value;
+
+      request = new JX.Request(config.uri, function(r) {
+        preview && JX.DOM.setContent(preview, JX.HTML(r));
+        min = new Date().getTime() + 500;
+        defer && defer.stop();
+        defer = JX.defer(check, 500);
+      });
+      request.listen('finally', function() { request = null; });
+      request.setData({action : aval, content : cval});
+      // If we don't get a response back soon, retry on the next action.
+      request.setTimeout(2000);
+      request.send();
+    } else {
+      defer = JX.defer(check, 2000);
+    }
+  }
+
+  JX.DOM.listen(content, 'keydown', null, check);
+  JX.DOM.listen(action,  'change',  null, check);
+
+  check();
+});