1 files changed, 111 insertions, 0 deletions
diff --git a/webapp/static/ajax.js b/webapp/static/ajax.js
new file mode 100644
index 0000000000..bc80e9bd7f
--- /dev/null
+++ b/webapp/static/ajax.js
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2008 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+var PROGRESS_ELEMENT_ID = "ajax_progress";
+var CONNECTION_ERROR_ELEMENT_ID = "ajax_error";
+
+var g_filesLoading = 0;
+
+/**
+ * Asynchronously get a url that contains a json file, and call the callback
+ * when done.
+ *
+ * The callback should have the following prototype:
+ *  callback(boolean success, Object result)
+ *
+ * Returns an object that can be used to cancel the request.
+ */
+function get_file_contents(url, callback) {
+    var running = true;
+
+    function set_progress_visibility(visible) {
+        var progress = document.getElementById(PROGRESS_ELEMENT_ID);
+        if (progress) {
+            progress.style.display = visible ? "block" : "none";
+        }
+    }
+
+    show_bad_connection_error(null);
+
+    var req;
+    if (window.XMLHttpRequest) {
+        req = new XMLHttpRequest();
+    } else if (window.ActiveXObject) {
+        req = new ActiveXObject("Microsoft.XMLHTTP");
+    } else {
+        return;
+    }
+
+    g_filesLoading++;
+    if (g_filesLoading > 0) {
+        set_progress_visibility(true);
+    }
+
+    req.open("GET", url, true);
+
+    req.onreadystatechange = function() {
+        if (req.readyState == 4) {
+            if (req.status == 200) {
+                callback(true, req.responseText);
+            } else {
+                callback(false, null);
+            }
+            g_filesLoading--;
+            if (g_filesLoading == 0) {
+                set_progress_visibility(false);
+            }
+            running = false;
+        }
+    };
+
+    req.send(null);
+
+
+    var controller = new Object();
+    controller.cancel = function() {
+        req.abort();
+        if (running) {
+            g_filesLoading--;
+            if (g_filesLoading == 0) {
+                set_progress_visibility(false);
+            }
+            running = false;
+        }
+    };
+    return controller;
+}
+
+/**
+ * like get_file_contents, but converts the result to a json object
+ */
+function get_json(url, callback) {
+    return get_file_contents(url, function(success, data) {
+                callback(success, eval("(" + data + ")"));
+            });
+}
+
+function show_bad_connection_error(err) {
+    var errorDiv = document.getElementById(CONNECTION_ERROR_ELEMENT_ID);
+    if (errorDiv) {
+        if (err) {
+            errorDiv.style.display = "block";
+        } else {
+            errorDiv.style.display = "none";
+        }
+    }
+}
+
+