Code create element:
 function createimg(url_img){
    var create_img = document.createElement('img');
    create_img.setAttribute('class','imgg');
    create_img.setAttribute('src',url_img);
    document.getElementsByClassName('thumb')[0].appendChild(create_img);
}
Code Jquery: jquery is not working
$(document).ready(function(){
    $(".imgg").mouseover(function(){
        console.log('ok');
    });
});
I try with tag body is working fine:
$(document).ready(function(){
        $("body").mouseover(function(){
            console.log('ok');
        });
    });