[PATCH 2 of 5] hgweb: add makeRequest javascript function

[Alexander Plavin]

# HG changeset patch
# User Alexander Plavin <alexander at plav.in>
# Date 1378459857 -14400
#      Fri Sep 06 13:30:57 2013 +0400
# Node ID 9ae2d8d0823a34439d94335b42aea155531850f4
# Parent  1a20a7cc2b08c3b720ac02df815905e01276a90a
hgweb: add makeRequest javascript function

This function performs an asynchronous HTTP request and calls provided
callbacks:
- onstart: request is sent
- onsuccess: response is received
- onerror: some error occured
- oncomplete: response is fully processed and all other callbacks finished

diff -r 1a20a7cc2b08 -r 9ae2d8d0823a mercurial/templates/static/mercurial.js
--- a/mercurial/templates/static/mercurial.js	Fri Sep 06 13:30:57 2013 +0400
+++ b/mercurial/templates/static/mercurial.js	Fri Sep 06 13:30:57 2013 +0400
@@ -304,3 +304,27 @@
         return String(replacements[p1]);
     });
 }
+
+function makeRequest(url, method, onstart, onsuccess, onerror, oncomplete) {
+    xfr = new XMLHttpRequest();
+    xfr.onreadystatechange = function() {
+        if (xfr.readyState === 4) {
+            try {
+                if (xfr.status === 200) {
+                    onsuccess(xfr.responseText);
+                } else {
+                    throw 'server error';
+                }
+            } catch (e) {
+                onerror(e);
+            } finally {
+                oncomplete();
+            }
+        }
+    };
+
+    xfr.open(method, url);
+    xfr.send();
+    onstart();
+    return xfr;
+}