Im using bootstrap 3.2 and Jquery 1.11.1. The webapp works fine in all major browser including IE 10 and 11. Im using the .collapse('toggle') function for the navbar. In other browsers it adds the "in" class but for some reason that does not happen the first time I open the menu in IE 9. Subsequent calls add the ".in" class and remove it. The first click does not trigger it.
How to make it work properly in IE9?
You got your CSS from CDN (bootstrapcdn.com) respond.js only works for local files. So try your website on IE9 with a local copy of bootstrap.css. Or read: CDN/X-Domain Setup
Update:
Please read: http://getbootstrap.com/getting-started/#support
In addition, Internet Explorer 8 requires the use of respond.js to enable media query support.
See also: https://github.com/scottjehl/Respond
For this reason, the basic template contains these lines in the <head> section:
<!-- HTML5 shim and Respond.js IE8 support of HTML5 elements and media queries -->
<!--[if lt IE 9]>
<script src="../../assets/js/html5shiv.js"></script>
<script src="../../assets/js/respond.min.js"></script>
<![endif]-->