Twitter Bootstrap add active class to li

For Bootstrap 3:

var url = window.location;
// Will only work if string in href matches with location
$('ul.nav a[href="'+ url +'"]').parent().addClass('active');

// Will also work for relative and absolute hrefs
$('ul.nav a').filter(function() {
    return this.href == url;
}).parent().addClass('active');

Update

For Bootstrap 4:

var url = window.location;
// Will only work if string in href matches with location
$('ul.navbar-nav a[href="'+ url +'"]').parent().addClass('active');

// Will also work for relative and absolute hrefs
$('ul.navbar-nav a').filter(function() {
    return this.href == url;
}).parent().addClass('active');

We managed to fix in the end:

/*menu handler*/
$(function(){
  function stripTrailingSlash(str) {
    if(str.substr(-1) == '/') {
      return str.substr(0, str.length - 1);
    }
    return str;
  }

  var url = window.location.pathname;  
  var activePage = stripTrailingSlash(url);

  $('.nav li a').each(function(){  
    var currentPage = stripTrailingSlash($(this).attr('href'));

    if (activePage == currentPage) {
      $(this).parent().addClass('active'); 
    } 
  });
});