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gitweb.js: Workaround for IE8 bug

In Internet Explorer 8 (IE8) the 'blame_incremental' view, which uses
JavaScript to generate blame info using AJAX, sometimes hang at the
beginning (at 0%) of blaming, e.g. for larger files with long history
like git's own gitweb/gitweb.perl.

The error shown by JavaScript console is "Unspecified error" at char:2
of the following line in gitweb/gitweb.js:

  if (xhr.readyState === 3 && xhr.status !== 200) {

Debugging it using IE8 JScript debuger shown that the error occurs
when trying to access xhr.status (xhr is XMLHttpRequest object).
Watch for xhr object shows 'Unspecified error.' as "value" of
xhr.status, and trying to access xhr.status from console throws error.

This bug is some intermittent bug, depending on XMLHttpRequest timing,
as it doesn't occur in all cases.  It is probably caused by the fact
that handleResponse is called from timer (pollTimer), to work around
the fact that some browsers call onreadystatechange handler only once
for each state change, and not like required for 'blame_incremental'
as soon as new data is available from server.  It looks like xhr
object is not properly initialized; still it is a bug to throw an
error when accessing xhr.status (and not use 'null' or 'undefined' as

Work around this bug in IE8 by using try-catch block when accessing

Signed-off-by: Jakub Narebski <>
Signed-off-by: Junio C Hamano <>
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1 parent 026680f commit b2c2e4c22c6a4fe151f02380d247cf3d9a9d5d1e @jnareb jnareb committed with gitster Jan 24, 2010
Showing with 6 additions and 1 deletion.
  1. +6 −1 gitweb/gitweb.js
7 gitweb/gitweb.js
@@ -779,7 +779,12 @@ function handleResponse() {
// the server returned error
- if (xhr.readyState === 3 && xhr.status !== 200) {
+ // try ... catch block is to work around bug in IE8
+ try {
+ if (xhr.readyState === 3 && xhr.status !== 200) {
+ return;
+ }
+ } catch (e) {
if (xhr.readyState === 4 && xhr.status !== 200) {

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