Ff JQuery can not listen to the keyup input event solution

$(document).ready(function(){
    $('#news_title').bind('input',fun).bind('keyup',fun);
});
//function list
var fun=function(){
    value=$(this).val();
    $('.prev').text(value);
}

Bind (' input 'fun)   For keyup under ff

Bind (' keyup 'fun) used in Internet explorer