Open Source Monorail

appengine/monorail/static/js/graveyard/xmlhttp.js

+/* Copyright 2016 The Chromium Authors. All Rights Reserved.
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file or at
+ * https://developers.google.com/open-source/licenses/bsd
+ */
+
+/**
+ * @fileoverview A bunch of XML HTTP recipes used to do RPC from JavaScript
+ */
+
+
+/**
+ * The active x identifier used for ie.
+ * @type String
+ * @private
+ */
+var XH_ieProgId_;
+
+
+// Domain for XMLHttpRequest readyState
+var XML_READY_STATE_UNINITIALIZED = 0;
+var XML_READY_STATE_LOADING = 1;
+var XML_READY_STATE_LOADED = 2;
+var XML_READY_STATE_INTERACTIVE = 3;
+var XML_READY_STATE_COMPLETED = 4;
+
+
+/**
+ * Initialize the private state used by other functions.
+ * @private
+ */
+function XH_XmlHttpInit_() {
+  // The following blog post describes what PROG IDs to use to create the
+  // XMLHTTP object in Internet Explorer:
+  // http://blogs.msdn.com/xmlteam/archive/2006/10/23/using-the-right-version-of-msxml-in-internet-explorer.aspx
+  // However we do not (yet) fully trust that this will be OK for old versions
+  // of IE on Win9x so we therefore keep the last 2.
+  // Versions 4 and 5 have been removed because 3.0 is the preferred "fallback"
+  // per the article above.
+  // - Version 5 was built for Office applications and is not recommended for
+  //   web applications.
+  // - Version 4 has been superseded by 6 and is only intended for legacy apps.
+  // - Version 3 has a wide install base and is serviced regularly with the OS.
+
+  /**
+   * Candidate Active X types.
+   * @type Array.<String>
+   * @private
+   */
+  var XH_ACTIVE_X_IDENTS = ["MSXML2.XMLHTTP.6.0", "MSXML2.XMLHTTP.3.0",
+                            "MSXML2.XMLHTTP", "Microsoft.XMLHTTP"];
+
+  if (typeof XMLHttpRequest == "undefined" &&
+      typeof ActiveXObject != "undefined") {
+    for (var i = 0; i < XH_ACTIVE_X_IDENTS.length; i++) {
+      var candidate = XH_ACTIVE_X_IDENTS[i];
+
+      try {
+        new ActiveXObject(candidate);
+        XH_ieProgId_ = candidate;
+        break;
+      } catch (e) {
+        // do nothing; try next choice
+      }
+    }
+
+    // couldn't find any matches
+    if (!XH_ieProgId_) {
+      throw Error("Could not create ActiveXObject. ActiveX might be disabled," +
+                  " or MSXML might not be installed.");
+    }
+  }
+}
+
+
+XH_XmlHttpInit_();
+
+
+/**
+ * Create and return an xml http request object that can be passed to
+ * {@link #XH_XmlHttpGET} or {@link #XH_XmlHttpPOST}.
+ */
+function XH_XmlHttpCreate() {
+  if (XH_ieProgId_) {
+    return new ActiveXObject(XH_ieProgId_);
+  } else {
+    return new XMLHttpRequest();
+  }
+}
+
+
+/**
+ * Send a get request.
+ * @param {XMLHttpRequest} xmlHttp as from {@link XH_XmlHttpCreate}.
+ * @param {string} url the service to contact
+ * @param {Function} handler function called when the response is received.
+ */
+function XH_XmlHttpGET(xmlHttp, url, handler) {
+  xmlHttp.open("GET", url, true);
+  xmlHttp.onreadystatechange = handler;
+  XH_XmlHttpSend(xmlHttp, null);
+}
+
+/**
+ * Send a post request.
+ * @param {XMLHttpRequest} xmlHttp as from {@link XH_XmlHttpCreate}.
+ * @param {string} url the service to contact
+ * @param {string} data the request content.
+ * @param {Function} handler function called when the response is received.
+ */
+function XH_XmlHttpPOST(xmlHttp, url, data, handler) {
+  xmlHttp.open("POST", url, true);
+  xmlHttp.onreadystatechange = handler;
+  xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
+  XH_XmlHttpSend(xmlHttp, data);
+}
+
+/**
+ * Calls 'send' on the XMLHttpRequest object and calls a function called 'log'
+ * if any error occured.
+ *
+ * @deprecated This dependes on a function called 'log'. You are better off
+ * handling your errors on application level.
+ *
+ * @param {XMLHttpRequest} xmlHttp as from {@link XH_XmlHttpCreate}.
+ * @param {string|null} data the request content.
+ */
+function XH_XmlHttpSend(xmlHttp, data) {
+  try {
+    xmlHttp.send(data);
+  } catch (e) {
+    // You may want to log/debug this error one that you should be aware of is
+    // e.number == -2146697208, which occurs when the 'Languages...' setting in
+    // IE is empty.
+    // This is not entirely true. The same error code is used when the user is
+    // off line.
+    console.log('XMLHttpSend failed ' + e.toString() + '<br>' + e.stack);
+    throw e;
+  }
+}