i solve the problem using this script, tnx all!
Modernizr.load(
{
test: /MSIE ([0-9]{1,}[\.0-9]{0,})/.test(navigator.userAgent),
yep: '/javascripts/assets/jquery/jquery-1.9.1.min.js',
nope: '/javascripts/assets/zepto/zepto.min.js',
complete:function()
{
if(!window.jQuery)
{
Zepto.browser = {webkit: true}
window.jQuery = Zepto
console.log('Zepto')
}
Modernizr.load(
{
load:'/javascripts/assets/bootstrap/bootstrap.js',
complete:function()
{
console.log('Loaded!')
},
})
},
});